Elements of Chemistry, by Antoine Lavoisier

Part II.

Of the Combination of Acids with Salifiable Bases, and of the Formation of Neutral Salts.

Introduction.

If I had strictly followed the plan I at first laid down for the conduct of this work, I would have confined myself, in the Tables and accompanying observations which compose this Second Part, to short definitions of the several known acids, and abridged accounts of the processes by which they are obtainable, with a mere nomenclature or enumeration of the neutral salts which result from the combination of these acids with the various salifiable bases. But I afterwards found that the addition of similar Tables of all the simple substances which enter into the composition of the acids and oxyds, together with the various possible combinations of these elements, would add greatly to the utility of this work, without being any great increase to its size. These additions, which are all contained in the twelve first sections of this Part, and the Tables annexed to these, form a kind of recapitulation of the first fifteen Chapters of the First Part: The rest of the Tables and Sections contain all the saline combinations.

It must be very apparent that, in this Part of the Work, I have borrowed greatly from what has been already published by Mr de Morveau in the First Volume of the Encyclopedie par ordre des Matières. I could hardly have discovered a better source of information, especially when the difficulty of consulting books in foreign languages is considered. I make this general acknowledgment on purpose to save the trouble of references to Mr de Morveau's work in the course of the following part of mine.

Table of Simple Substances.

Simple substances belonging to all the kingdoms of nature, which may be considered as the elements of bodies.
New Names. Correspondent old Names.
Light Light.
Caloric {Heat.
{Principle or element of heat.
{Fire. Igneous fluid.
{Matter of fire and of heat.
Oxygen {Dephlogisticated air.
{Empyreal air.
{Vital air, or
{Base of vital air.
Azote {Phlogisticated air or gas.
{Mephitis, or its base.
Hydrogen {Inflammable air or gas, or the base of inflammable air.
Oxydable and Acidifiable simple Substance not Metallic.
New Names.   Correspondent old names.
Sulphur
Phosphorous
Charcoal
} The same names.
Muriatic radical
Fluoric radical
Boracic radical
} Still unknown.
Oxydable and Acidifiable simple Metallic Bodies
New Names.     Correspondent Old Names.
Antimony } { Antimony.
Arsenic } { Arsenic.
Bismuth } { Bismuth.
Cobalt } { Cobalt.
Copper } { Copper.
Gold } { Gold.
Iron } { Iron.
Lead } Regulus of { Lead.
Manganese } { Manganese.
Mercury } { Mercury.
Molybdena } { Molybdena.
Nickel } { Nickel.
Platina } { Platina.
Silver } { Silver.
Tin } { Tin.
Tungstein } { Tungstein.
Zinc } { Zinc.
Salifiable simple Earthy Substances.
New Names. Correspondent old Names.
 
Lime {Chalk, calcareous earth.
{Quicklime.
 
Magnesia {Magnesia, base of Epsom salt.
{Calcined or caustic magnesia.
 
Barytes Barytes, or heavy earth.
Argill Clay, earth of alum.
Silex Siliceous or vitrifiable earth.

Sect. I.Observations upon the Table of Simple Substances.

The principle object of chemical experiments is to decompose natural bodies, so as separately to examine the different substances which enter into their composition. By consulting chemical systems, it will be found that this science of chemical analysis has made rapid progress in our own times. Formerly oil and salt were considered as elements of bodies, whereas later observation and experiment have shown that all salts, instead of being simple, are composed of an acid united to a base. The bounds of analysis have been greatly enlarged by modern discoveries36; the acids are shown to be composed of oxygen, as an acidifying principle common to all, united in each to a particular base. I have proved what Mr Haffenfratz had before advanced, that these radicals of the acids are not all simple elements, many of them being, like the oily principle, composed of hydrogen and charcoal. Even the bases of neutral salts have been proved by Mr Berthollet to be compounds, as he has shown that ammoniac is composed of azote and hydrogen.

Thus, as chemistry advances towards perfection, by dividing and subdividing, it is impossible to say where it is to end; and these things we at present suppose simple may soon be found quite otherwise. All we dare venture to affirm of any substance is, that it must be considered as simple in the present state of our knowledge, and so far as chemical analysis has hitherto been able to show. We may even presume that the earths must soon cease to be considered as simple bodies; they are the only bodies of the salifiable class which have no tendency to unite with oxygen; and I am much inclined to believe that this proceeds from their being already saturated with that element. If so, they will fall to be considered as compounds consisting of simple substances, perhaps metallic, oxydated to a certain degree. This is only hazarded as a conjecture; and I trust the reader will take care not to confound what I have related as truths, fixed on the firm basis of observation and experiment, with mere hypothetical conjectures.

The fixed alkalies, potash, and soda, are omitted in the foregoing Table, because they are evidently compound substances, though we are ignorant as yet what are the elements they are composed of.

36 See Memoirs of the Academy for 1776, p. 671. and for 1778, p. 535 — A.

Table of compound oxydable and acidifiable bases.

Names of the radicals.
Oxydable or acidifiable base, from the mineral kingdom. Nitro-muriatic radical or base of the acid formerly called aqua regia.
Oxydable or acidifiable hydro-carbonous or carbono-hydrous radicals from the vegetable kingdom. Tartarous radical or base.
Malic. Radicals
Citric.
Pyro-lignous.
Pyro-mucous.
Pyro-tartarous.
Oxalic.
Acetous.
Succinic.
Benzoic.
Camphoric.
Gallic.
Oxydable or acidifiable radicals from the animal kingdom, which mostly contain azote, and frequently phosphorus. Lactic.
Saccholactic.
Formic.
Bombic.
Sebacic.
Lithic.
Prussic.

Note.— The radicals from the vegetable kingdom are converted by a first degree of oxygenation into vegetable oxyds, such as sugar, starch, and gum or mucus: Those of the animal kingdom by the same means form animal oxyds, as lymph, &c. — A.

Sect. II.Observations upon the Table of Compound Radicals.

The older chemists being unacquainted with the composition of acids, and not suspecting them to be formed by a peculiar radical or base for each, united to an acidifying principle or element common to all, could not consequently give any name to substances of which they had not the most distant idea. We had therefore to invent a new nomenclature for this subject, though we were at the same time sensible that this nomenclature must be susceptible of great modification when the nature of the compound radicals shall be better understood37.

The compound oxydable and acidifiable radicals from the vegetable and animal kingdoms, enumerated in the foregoing table, are not hitherto reducible to systematic nomenclature, because their exact analysis is as yet unknown. We only know in general, by some experiments of my own, and some made by Mr Hassenfratz, that most of the vegetable acids, such as the tartarous, oxalic, citric, malic, acetous, pyro-tartarous, and pyromucous, have radicals composed of hydrogen and charcoal, combined in such a way as to form single bases, and that these acids only differ from each other by the proportions in which these two substances enter into the composition of their bases, and by the degree of oxygenation which these bases have received. We know farther, chiefly from the experiments of Mr Berthollet, that the radicals from the animal kingdom, and even some of those from vegetables, are of a more compound nature, and, besides hydrogen and charcoal, that they often contain azote, and sometimes phosphorus; but we are not hitherto possessed of sufficiently accurate experiments for calculating the proportions of these several substances. We are therefore forced, in the manner of the older chemists, still to name these acids after the substances from which they are procured. There can be little doubt that these names will be laid aside when our knowledge of these substances becomes more accurate and extensive; the terms hydro-carbonous, hydro-carbonic, carbono-hydrous, and carbono hydric38, will then become substituted for those we now employ, which will then only remain as testimonies of the imperfect state in which this part of chemistry was transmitted to us by our predecessors.

It is evident that the oils, being composed of hydrogen and charcoal combined, are true carbono-hydrous or hydro-carbonous radicals; and, indeed, by adding oxygen, they are convertible into vegetable oxyds and acids, according to their degrees of oxygenation. We cannot, however, affirm that oils enter in their entire state into the composition of vegetable oxyds and acids; it is possible that they previously lose a part either of their hydrogen or charcoal, and that the remaining ingredients no longer exist in the proportions necessary to constitute oils. We still require farther experiments to elucidate these points.

Properly speaking, we are only acquainted with one compound radical from the mineral kingdom, the nitro-muriatic, which is formed by the combination of azote with the muriatic radical. The other compound mineral acids have been much less attended to, from their producing less striking phenomena.

37 See Part I. Chap. XI. upon this subject. — A.

38 See Part I. Chap. XI. upon the application of these names according to the proportions of the two ingredients. — A

Sect. III.Observations upon the Combinations of Light and Caloric with different Substances.

I have not constructed any table of the combinations of light and caloric with the various simple and compound substances, because our conceptions of the nature of these combinations are not hitherto sufficiently accurate. We know, in general, that all bodies in nature are imbued, surrounded, and penetrated in every way with caloric, which fills up every interval left between their particles; that, in certain cases, caloric becomes fixed in bodies, so as to constitute a part even of their solid substance, though it more frequently acts upon them with a repulsive force, from which, or from its accumulation in bodies to a greater or lesser degree, the transformation of solids into fluids, and of fluids to aëriform elasticity, is entirely owing. We have employed the generic name gas to indicate this aëriform state of bodies produced by a sufficient accumulation of caloric; so that, when we wish to express the aëriform state of muriatic acid, carbonic acid, hydrogen, water, alkohol, &c. we do it by adding the word gas to their names; thus muriatic acid gas, carbonic acid gas, hydrogen gas, aqueous gas, alkoholic gas, &c.

The combinations of light, and its mode of acting upon different bodies, is still less known. By the experiments of Mr Berthollet, it appears to have great affinity with oxygen, is susceptible of combining with it, and contributes alongst with caloric to change it into the state of gas. Experiments upon vegetation give reason to believe that light combines with certain parts of vegetables, and that the green of their leaves, and the various colours of their flowers, is chiefly owing to this combination. This much is certain, that plants which grow in darkness are perfectly white, languid, and unhealthy, and that to make them recover vigour, and to acquire their natural colours, the direct influence of light is absolutely necessary. Somewhat similar takes place even upon animals: Mankind degenerate to a certain degree when employed in sedentary manufactures, or from living in crowded houses, or in the narrow lanes of large cities; whereas they improve in their nature and constitution in most of the country labours which are carried on in the open air. Organization, sensation, spontaneous motion, and all the operations of life, only exist at the surface of the earth, and in places exposed to the influence of light. Without it nature itself would be lifeless and inanimate. By means of light, the benevolence of the Deity hath filled the surface of the earth with organization, sensation, and intelligence. The fable of Promotheus might perhaps be considered as giving a hint of this philosophical truth, which had even presented itself to the knowledge of the ancients. I have intentionally avoided any disquisitions relative to organized bodies in this work, for which reason the phenomena of respiration, sanguification, and animal heat, are not considered; but I hope, at some future time, to be able to elucidate these curious subjects.

Table of the binary Combinations of Oxygen with simple Substances

[Trancriber's note: The following table has been split into four sections ease reading]
Combinations of oxygen with simple non-metallic substances. Names of the simple substances. First degree of oxygenation.
New Names. Ancient Names.
Caloric Oxygen gas Vital or dephlogisticated air
Hydrogen. Water(A).  
Azote Nitrous oxyd, or base of nitrous gas Nitrous gas or air
Charcoal Oxyd of charcoal, or carbonic oxyd Unknown
Sulphur Oxyd of sulphur Soft sulphur
Phosphorus Oxyd of phosphorus {Residuum from the combustion of phosphorus  
Muriatic radical Muriatic oxyd Unknown
Fluoric radical Fluoric oxyd Unknown
Boracic radical Boracic oxyd Unknown
       
Combinations of oxygen with the simple metallic substances. Antimony Grey oxyd of antimony Grey calx of antimony
Silver Oxyd of silver Calx of silver
Arsenic Grey oxyd of arsenic Grey calx of arsenic
Bismuth Grey oxyd of bismuth Grey calx of bismuth
Cobalt Grey oxyd of cobalt Grey calx of cobalt
Copper Brown oxyd of copper Brown calx of copper
Tin Grey oxyd of tin Grey calx of tin
Iron Black oxyd of iron Martial ethiops
Manganese Black oxyd of manganese Black calx of manganese
Mercury Black oxyd of mercury Ethiops mineral(B)
Molybdena Oxyd of molybdena Calx of molybdena
Nickel Oxyd of nickel Calx of nickel
Gold Yellow oxyd of gold Yellow calx of gold
Platina Yellow oxyd of platina Yellow calx of platina
Lead Grey oxyd of lead Grey calx of lead
Tungstein Oxyd of Tungstein Calx of Tungstein
Zinc Grey oxyd of zinc Grey calx of zinc
Combinations of oxygen with simple non-metallic substances. Names of the simple substances. Second degree of oxygenation.
New Names. Ancient Names.
Caloric    
Hydrogen.    
Azote Nitrous acid Smoaking nitrous acid
Charcoal Carbonous acid Unknown
Sulphur Sulphurous acid Sulphureous acid
Phosphorus Phosphorous acid Volatile acid of phosphorus
Muriatic radical Muriatous acid Unknown
Fluoric radical Fluorous acid Unknown
Boracic radical Boracous acid Unknown
     
Combinations of oxygen with the simple metallic substances. Antimony White oxyd of antimony White calx of antimony, diaphoretic antimony
Silver    
Arsenic White oxyd of arsenic White calx of arsenic
Bismuth White oxyd of bismuth White calx of bismuth
Cobalt    
Copper Blue and green oxyds of copper Blue and green calces of copper
Tin White oxyd of tin White calx of tin, or putty of tin
Iron Yellow and red oxyds of iron Ochre and rust of iron
Manganese White oxyd of manganese White calx of manganese
Mercury Yellow and red oxyds of mercury Turbith mineral, red precipitate, calcinated mercury, precipitate per se
Molybdena    
Nickel
Gold Red oxyd of gold Red calx of gold, purple precipitate of cassius
Platina    
Lead Yellow and red oxyds of lead Massicot and minium
Tungstein
Zinc White oxyd of zinc White calx of zinc, pompholix




Combinations of oxygen with simple non-metallic substances. Names of the simple substances. Third degree of oxygenation.
New Names. Ancient Names.
Caloric    
Hydrogen.
Azote Nitric acid Pale, or not smoaking nitrous acid
Charcoal Carbonic acid Fixed air
Sulphur Sulphuric acid Vitriolic acid
Phosphorus Phosphoric acid Phosphoric acid
Muriatic radical Muriatic acid Marine acid
Fluoric radical Fluoric acid Unknown till lately
Boracic radical Boracic acid Homberg's sedative salt
       
Combinations of oxygen with the simple metallic substances. Antimony Antimonic acid  
Silver Argentic acid  
Arsenic Arseniac acid Acid of arsenic
Bismuth Bismuthic acid  
Cobalt Cobaltic acid  
Copper Cupric acid  
Tin Stannic acid  
Iron Ferric acid  
Manganese Manganesic acid  
Mercury Mercuric acid  
Molybdena Molybdic acid Acid of molybdena
Nickel Nickelic acid  
Gold Auric acid  
Platina Platinic acid  
Lead Plumbic acid  
Tungstein Tungstic acid Acid of Tungstein
Zinc Zincic acid  




Combinations of oxygen with simple non-metallic substances. Names of the simple substances. Fourth degree of oxygenation.
New Names. Ancient Names.
Caloric    
Hydrogen.    
Azote Oxygenated nitric Unknown acid
Charcoal Oxygenated carbonic acid Unknown
Sulphur Oxygenated sulphuric acid Unknown
Phosphorus Oxygenated phosphoric acid Unknown
Muriatic radical Oxygenated muriatic acid Dephlogisticated marine acid
Fluoric radical    
Boracic radical    
       
Combinations of oxygen with the simple metallic substances. Antimony    
Silver    
Arsenic Oxygenated arseniac acid Unknown
Bismuth    
Cobalt    
Copper    
Tin    
Iron    
Manganese    
Mercury    
Molybdena Oxygenated molybdic acid Unknown
Nickel    
Gold    
Platina    
Lead    
Tungstein Oxygenated Tungstic acid Unknown
Zinc    




[Note A: Only one degree of oxygenation of hydrogen is hitherto known. — A.]

[Note B: Ethiops mineral is the sulphuret of mercury; this should have been called black precipitate of mercury. — E.]

Sect. IV.Observations upon the Combinations of Oxygen with the simple Substances.

Oxygen forms almost a third of the mass of our atmosphere, and is consequently one of the most plentiful substances in nature. All the animals and vegetables live and grow in this immense magazine of oxygen gas, and from it we procure the greatest part of what we employ in experiments. So great is the reciprocal affinity between this element and other substances, that we cannot procure it disengaged from all combination. In the atmosphere it is united with caloric, in the state of oxygen gas, and this again is mixed with about two thirds of its weight of azotic gas.

Several conditions are requisite to enable a body to become oxygenated, or to permit oxygen to enter into combination with it. In the first place, it is necessary that the particles of the body to be oxygenated shall have less reciprocal attraction with each other than they have for the oxygen, which otherwise cannot possibly combine with them. Nature, in this case, may be assisted by art, as we have it in our power to diminish the attraction of the particles of bodies almost at will by heating them, or, in other words, by introducing caloric into the interstices between their particles; and, as the attraction of these particles for each other is diminished in the inverse ratio of their distance, it is evident that there must be a certain point of distance of particles when the affinity they possess with each other becomes less than that they have for oxygen, and at which oxygenation must necessarily take place if oxygen be present.

We can readily conceive that the degree of heat at which this phenomenon begins must be different in different bodies. Hence, on purpose to oxygenate most bodies, especially the greater part of the simple substances, it is only necessary to expose them to the influence of the air of the atmosphere in a convenient degree of temperature. With respect to lead, mercury, and tin, this needs be but little higher than the medium temperature of the earth; but it requires a more considerable degree of heat to oxygenate iron, copper, &c. by the dry way, or when this operation is not assisted by moisture. Sometimes oxygenation takes place with great rapidity, and is accompanied by great sensible heat, light, and flame; such is the combustion of phosphorus in atmospheric air, and of iron in oxygen gas. That of sulphur is less rapid; and the oxygenation of lead, tin, and most of the metals, takes place vastly slower, and consequently the disengagement of caloric, and more especially of light, is hardly sensible.

Some substances have so strong an affinity with oxygen, and combine with it in such low degrees of temperature, that we cannot procure them in their unoxygenated state; such is the muriatic acid, which has not hitherto been decomposed by art, perhaps even not by nature, and which consequently has only been found in the state of acid. It is probable that many other substances of the mineral kingdom are necessarily oxygenated in the common temperature of the atmosphere, and that being already saturated with oxygen, prevents their farther action upon that element.

There are other means of oxygenating simple substances besides exposure to air in a certain degree of temperature, such as by placing them in contact with metals combined with oxygen, and which have little affinity with that element. The red oxyd of mercury is one of the best substances for this purpose, especially with bodies which do not combine with that metal. In this oxyd the oxygen is united with very little force to the metal, and can be driven out by a degree of heat only sufficient to make glass red hot; wherefore such bodies as are capable of uniting with oxygen are readily oxygenated, by means of being mixed with red oxyd of mercury, and moderately heated. The same effect may be, to a certain degree, produced by means of the black oxyd of manganese, the red oxyd of lead, the oxyds of silver, and by most of the metallic oxyds, if we only take care to choose such as have less affinity with oxygen than the bodies they are meant to oxygenate. All the metallic reductions and revivifications belong to this class of operations, being nothing more than oxygenations of charcoal, by means of the several metallic oxyds. The charcoal combines with the oxygen and with caloric, and escapes in form of carbonic acid gas, while the metal remains pure and revivified, or deprived of the oxygen which before combined with it in the form of oxyd.

All combustible substances may likewise be oxygenated by means of mixing them with nitrat of potash or of soda, or with oxygenated muriat of potash, and subjecting the mixture to a certain degree of heat; the oxygen, in this case, quits the nitrat or the muriat, and combines with the combustible body. This species of oxygenation requires to be performed with extreme caution, and only with very small quantities; because, as the oxygen enters into the composition of nitrats, and more especially of oxygenated muriats, combined with almost as much caloric as is necessary for converting it into oxygen gas, this immense quantity of caloric becomes suddenly free the instant of the combination of the oxygen with the combustible body, and produces such violent explosions as are perfectly irresistible.

By the humid way we can oxygenate most combustible bodies, and convert most of the oxyds of the three kingdoms of nature into acids. For this purpose we chiefly employ the nitric acid, which has a very slight hold of oxygen, and quits it readily to a great number of bodies by the assistance of a gentle heat. The oxygenated muriatic acid may be used for several operations of this kind, but not in them all.

I give the name of binary to the combinations of oxygen with the simple substances, because in these only two elements are combined. When three substances are united in one combination I call it ternary, and quaternary when the combination consists of four substances united.

Table of the combinations of Oxygen with the compound radicals.

Names of the radicals. Names of the resulting acids.
New nomenclature. Old nomenclature.
Nitro muriatic radical Nitro muriatic acid Aqua regia.
(A)
Tartaric Tartarous acid Unknown till lately.
Malic Malic acid Ditto.
Citric Citric acid Acid of lemons.
Pyro-lignous Pyro-lignous acid Empyreumatic acid of wood.
Pyro-mucous Pyro-mucous acid Empyr. acid of sugar.
Pyro-tartarous Pyro-tartarous acid Empyr. acid of tartar.
Oxalic Oxalic acid Acid of sorel.
Acetic Acetous acid Vinegar, or acid of vinegar.
Acetic acid Radical vinegar.
Succinic Succinic acid Volatile salt of amber.
Benzoic Benzotic acid Flowers of benzoin.
Camphoric Camphoric acid Unknown till lately.
Gallic Gallic acid The astringent principle of vegetables.
 
(B)
Lactic Lactic acid Acid of sour whey.
Saccholactic Saccholactic acid Unknown till lately.
Formic Formic acid Acid of ants.
Bombic Bombic acid Unknown till lately.
Sebacic Sebacic acid Ditto.
Lithic Lithic acid Urinary calculus.
Prussic Prussic acid Colouring matter of Prussian blue.

[Note A: These radicals by a first degree of oxygenation form vegetable oxyds, as sugar, starch, mucus, &c. — A.]

[Note B: These radicals by a first degree of oxygenation form the animal oxyds, as lymph, red part of the blood, animal secretions, &c. — A.]

Sect. V.Observations upon the Combinations of Oxygen with the Compound Radicals.

I published a new theory of the nature and formation of acids in the Memoirs of the Academy for 1776, p. 671. and 1778, p. 535. in which I concluded, that the number of acids must be greatly larger than was till then supposed. Since that time, a new field of inquiry has been opened to chemists; and, instead of five or six acids which were then known, near thirty new acids have been discovered, by which means the number of known neutral salts have been increased in the same proportion. The nature of the acidifiable bases, or radicals of the acids, and the degrees of oxygenation they are susceptible of, still remain to be inquired into. I have already shown, that almost all the oxydable and acidifiable radicals from the mineral kingdom are simple, and that, on the contrary, there hardly exists any radical in the vegetable, and more especially in the animal kingdom, but is composed of at least two substances, hydrogen and charcoal, and that azote and phosphorus are frequently united to these, by which we have compound radicals of two, three, and four bases or simple elements united.

From these observations, it appears that the vegetable and animal oxyds and acids may differ from each other in three several ways: 1st, According to the number of simple acidifiable elements of which their radicals are composed: 2dly, According to the proportions in which these are combined together: And, 3dly, According to their different degrees of oxygenation: Which circumstances are more than sufficient to explain the great variety which nature produces in these substances. It is not at all surprising, after this, that most of the vegetable acids are convertible into each other, nothing more being requisite than to change the proportions of the hydrogen and charcoal in their composition, and to oxygenate them in a greater or lesser degree. This has been done by Mr Crell in some very ingenious experiments, which have been verified and extended by Mr Hassenfratz. From these it appears, that charcoal and hydrogen, by a first oxygenation, produce tartarous acid, oxalic acid by a second degree, and acetous or acetic acid by a third, or higher oxygenation; only, that charcoal seems to exist in a rather smaller proportion in the acetous and acetic acids. The citric and malic acids differ little from the preceding acids.

Ought we then to conclude that the oils are the radicals of the vegetable and animal acids? I have already expressed my doubts upon this subject: 1st, Although the oils appear to be formed of nothing but hydrogen and charcoal, we do not know if these are in the precise proportion necessary for constituting the radicals of the acids: 2dly, Since oxygen enters into the composition of these acids equally with hydrogen and charcoal, there is no more reason for supposing them to be composed of oil rather than of water or of carbonic acid. It is true that they contain the materials necessary for all these combinations, but then these do not take place in the common temperature of the atmosphere; all the three elements remain combined in a state of equilibrium, which is readily destroyed by a temperature only a little above that of boiling water39.

39 See Part I. Chap. XII. upon this subject. — A.

Table of the Binary Combinations of Azote with the Simple Substances.

Simple Substances. Results of the Combinations.
New Nomenclature. Old Nomenclature.
Caloric Azotic gas Phlogisticated air, or Mephitis.
Hydrogen Ammoniac Volatile alkali.
Oxygen Nitrous oxyd Base of Nitrous gas.
Nitrous acid Smoaking nitrous acid.
Nitric acid Pale nitrous acid.
Oxygenated nitric acid Unknown.
Charcoal This combination is hitherto unknown; should it ever be discovered, it will be called, according to the principles of our nomenclature, Azuret of Charcoal. Charcoal dissolves in azotic gas, and forms carbonated azotic gas.
Phosphorus. Azuret of phosphorus. Still unknown.
Sulphur Azuret of sulphur. Still unknown. We know that sulphur dissolves in azotic gas, forming sulphurated azotic gas.
Compound radicals Azote combines with charcoal and hydrogen, and sometimes with phosphorus, in the compound oxydable and acidifiable bases, and is generally contained in the radicals of the animal acids.
Metallic substances Such combinations are hitherto unknown; if ever discovered, they will form metallic azurets, as azuret of gold, of silver, &c.
Lime Entirely unknown. If ever discovered, they will form azuret of lime, azuret of magnesia, &c.
Magnesia
Barytes
Argill
Potash
Soda

Sect. VI. —Observations upon the Combinations of Azote with the Simple Substances.

Azote is one of the most abundant elements; combined with caloric it forms azotic gas, or mephitis, which composes nearly two thirds of the atmosphere. This element is always in the state of gas in the ordinary pressure and temperature, and no degree of compression or of cold has been hitherto capable of reducing it either to a solid or liquid form. This is likewise one of the essential constituent elements of animal bodies, in which it is combined with charcoal and hydrogen, and sometimes with phosphorus; these are united together by a certain portion of oxygen, by which they are formed into oxyds or acids according to the degree of oxygenation. Hence the animal substances may be varied, in the same way with vegetables, in three different manners: 1st, According to the number of elements which enter into the composition of the base or radical: 2dly, According to the proportions of these elements: 3dly, According to the degree of oxygenation.

When combined with oxygen, azote forms the nitrous and nitric oxyds and acids; when with hydrogen, ammoniac is produced. Its combinations with the other simple elements are very little known; to these we give the name of Azurets, preserving the termination in uret for all nonoxygenated compounds. It is extremely probable that all the alkaline substances may hereafter be found to belong to this genus of azurets.

The azotic gas may be procured from atmospheric air, by absorbing the oxygen gas which is mixed with it by means of a solution of sulphuret of potash, or sulphuret of lime. It requires twelve or fifteen days to complete this process, during which time the surface in contact must be frequently renewed by agitation, and by breaking the pellicle which forms on the top of the solution. It may likewise be procured by dissolving animal substances in dilute nitric acid very little heated. In this operation, the azote is disengaged in form of gas, which we receive under bell glasses filled with water in the pneumato-chemical apparatus. We may procure this gas by deflagrating nitre with charcoal, or any other combustible substance; when with charcoal, the azotic gas is mixed with carbonic acid gas, which may be absorbed by a solution of caustic alkali, or by lime water, after which the azotic gas remains pure. We can procure it in a fourth manner from combinations of ammoniac with metallic oxyds, as pointed out by Mr de Fourcroy: The hydrogen of the ammoniac combines with the oxygen of the oxyd, and forms water, whilst the azote being left free escapes in form of gas.

The combinations of azote were but lately discovered: Mr Cavendish first observed it in nitrous gas and acid, and Mr Berthollet in ammoniac and the prussic acid. As no evidence of its decomposition has hitherto appeared, we are fully entitled to consider azote as a simple elementary substance.

Table of the Binary Combinations of Hydrogen with Simple Substances.

Simple Substances. Resulting Compounds.
New Nomenclature. Old Names.
Caloric Hydrogen gas Inflammable air.
Azote Ammoniac Volatile Alkali.
Oxygen Water Water.
Sulphur {Hydruret of sulphur, or }
{sulphuret of hydrogen } Hitherto unknown (A).
Phosphorus {Hydruret of phosphorus, or }
{phosphuret of hydrogen }
Charcoal {Hydro-carbonous, or } Not known till lately.
{carbono-hydrous radicals(B)}
Metallic {Metallic hydrurets(C), as} Hitherto unknown.
substances, as {hydruret of iron, &c.}
iron, &c. { }

[Note A: These combinations take place in the state of gas, and form, respectively, sulphurated and phosphorated oxygen gas — A.]

[Note B: This combination of hydrogen with charcoal includes the fixed and volatile oils, and forms the radicals of a considerable part of the vegetable and animal oxyds and acids. When it takes place in the state of gas it forms carbonated hydrogen gas. — A.]

[Note C: None of these combinations are known, and it is probable that they cannot exist, at least in the usual temperature of the atmosphere, owing to the great affinity of hydrogen for caloric. — A.]

Sect. VII.Observations upon Hydrogen, and its Combinations with Simple Substances.

Hydrogen, as its name expresses, is one of the constituent elements of water, of which it forms fifteen hundredth parts by weight, combined with eighty-five hundredth parts of oxygen. This substance, the properties and even existence of which was unknown till lately, is very plentifully distributed in nature, and acts a very considerable part in the processes of the animal and vegetable kingdoms. As it possesses so great affinity with caloric as only to exist in the state of gas, it is consequently impossible to procure it in the concrete or liquid state, independent of combination.

To procure hydrogen, or rather hydrogen gas, we have only to subject water to the action of a substance with which oxygen has greater affinity than it has to hydrogen; by this means the hydrogen is set free, and, by uniting with caloric, assumes the form of hydrogen gas. Red hot iron is usually employed for this purpose: The iron, during the process, becomes oxydated, and is changed into a substance resembling the iron ore from the island of Elba. In this state of oxyd it is much less attractible by the magnet, and dissolves in acids without effervescence.

Charcoal, in a red heat, has the same power of decomposing water, by attracting the oxygen from its combination with hydrogen. In this process carbonic acid gas is formed, and mixes with the hydrogen gas, but is easily separated by means of water or alkalies, which absorb the carbonic acid, and leave the hydrogen gas pure. We may likewise obtain hydrogen gas by dissolving iron or zinc in dilute sulphuric acid. These two metals decompose water very slowly, and with great difficulty, when alone, but do it with great ease and rapidity when assisted by sulphuric acid; the hydrogen unites with caloric during the process, and is disengaged in form of hydrogen gas, while the oxygen of the water unites with the metal in the form of oxyd, which is immediately dissolved in the acid, forming a sulphat of iron or of zinc.

Some very distinguished chemists consider hydrogen as the phlogiston of Stahl; and as that celebrated chemist admitted the existence of phlogiston in sulphur, charcoal, metals, &c. they are of course obliged to suppose that hydrogen exists in all these substances, though they cannot prove their supposition; even if they could, it would not avail much, since this disengagement of hydrogen is quite insufficient to explain the phenomena of calcination and combustion. We must always recur to the examination of this question, "Are the heat and light, which are disengaged during the different species of combustion, furnished by the burning body, or by the oxygen which combines in all these operations?" And certainly the supposition of hydrogen being disengaged throws no light whatever upon this question. Besides, it belongs to those who make suppositions to prove them; and, doubtless, a doctrine which without any supposition explains the phenomena as well, and as naturally, as theirs does by supposition, has at least the advantage of greater simplicity40.

40 Those who wish to see what has been said upon this great chemical question by Messrs de Morveau, Berthollet, De Fourcroy, and myself, may consult our translation of Mr Kirwan's Essay upon Phlogiston. — A.

Table of the Binary Combinations of Sulphur with Simple Substances.

Simple Substances. Resulting Compounds.
New Nomenclature. Old Nomenclature.
Caloric Sulphuric gas
 
{Oxyd of sulphur Soft sulphur.
Oxygen {Sulphurous acid Sulphureous acid.
{Sulphuric acid Vitriolic acid.
 
Hydrogen Sulphuret of hydrogen}
Azote azote} Unknown Combinations.
Phosphorus phosphorus}
Charcoal charcoal}
 
Antimony antimony Crude antimony.
Silver silver
Arsenic arsenic Orpiment, realgar.
Bismuth bismuth
Cobalt cobalt
Copper copper Copper pyrites.
Tin tin
Iron iron Iron pyrites.
Manganese manganese
Mercury mercury Ethiops mineral, cinnabar.
Molybdena molybdena
Nickel nickel
Gold gold
Platina platina
Lead lead Galena.
Tungstein tungstein
Zinc zinc Blende.
Potash potash Alkaline liver of sulphur with fixed vegetable alkali.
Soda soda Alkaline liver of sulphur with fixed mineral alkali.
Ammoniac ammoniac Volatile liver of sulphur, smoaking liquor of Boyle.
Lime lime Calcareous liver of sulphur.
Magnesia magnesia Magnesian liver of sulphur.
Barytes barytes Barytic liver of sulphur.
Argill argill Yet unknown.

Sect. VIII.Observations on Sulphur, and its Combinations.

Sulphur is a combustible substance, having a very great tendency to combination; it is naturally in a solid state in the ordinary temperature, and requires a heat somewhat higher than boiling water to make it liquify. Sulphur is formed by nature in a considerable degree of purity in the neighbourhood of volcanos; we find it likewise, chiefly in the state of sulphuric acid, combined with argill in aluminous schistus, with lime in gypsum, &c. From these combinations it may be procured in the state of sulphur, by carrying off its oxygen by means of charcoal in a red heat; carbonic acid is formed, and escapes in the state of gas; the sulphur remains combined with the clay, lime, &c. in the state of sulphuret, which is decomposed by acids; the acid unites with the earth into a neutral salt, and the sulphur is precipitated.

Table of the Binary Combinations of Phosphorus with the Simple Substances.

Simple Substances. Resulting Compounds.
Caloric Phosphoric gas.
 
{ Oxyd of phosphorus.
Oxygen { Phosphorous acid.
{ Phosphoric acid.
 
Hydrogen Phosphuret of hydrogen.
Azote Phosphuret of azote.
Sulphur Phosphuret of Sulphur.
Charcoal Phosphuret of charcoal.
Metallic substances Phosphuret of metals(A).
 
Potash}
Soda}
Ammoniac} Phosphuret of Potash, Soda, &c.(B)
Lime}
Barytes}
Magnesia}
Argill}

[Note A: Of all these combinations of phosphorus with metals, that with iron only is hitherto known, forming the substance formerly called Siderite; neither is it yet ascertained whether, in this combination, the phosphorus be oxygenated or not. — A.]

[Note B: These combinations of phosphorus with the alkalies and earths are not yet known; and, from the experiments of Mr Gengembre, they appear to be impossible — A.]

Sect. IX.Observations upon Phosphorus, and its Combinations.

Phosphorus is a simple combustible substance, which was unknown to chemists till 1667, when it was discovered by Brandt, who kept the process secret; soon after Kunkel found out Brandt's method of preparation, and made it public. It has been ever since known by the name of Kunkel's phosphorus. It was for a long time procured only from urine; and, though Homberg gave an account of the process in the Memoirs of the Academy for 1692, all the philosophers of Europe were supplied with it from England. It was first made in France in 1737, before a committee of the Academy at the Royal Garden. At present it is procured in a more commodious and more oeconomical manner from animal bones, which are real calcareous phosphats, according to the process of Messrs Gahn, Scheele, Rouelle, &c. The bones of adult animals being calcined to whiteness, are pounded, and passed through a fine silk sieve; pour upon the fine powder a quantity of dilute sulphuric acid, less than is sufficient for dissolving the whole. This acid unites with the calcareous earth of the bones into a sulphat of lime, and the phosphoric acid remains free in the liquor. The liquid is decanted off, and the residuum washed with boiling water; this water which has been used to wash out the adhering acid is joined with what was before decanted off, and the whole is gradually evaporated; the dissolved sulphat of lime cristallizes in form of silky threads, which are removed, and by continuing the evaporation we procure the phosphoric acid under the appearance of a white pellucid glass. When this is powdered, and mixed with one third its weight of charcoal, we procure very pure phosphorus by sublimation. The phosphoric acid, as procured by the above process, is never so pure as that obtained by oxygenating pure phosphorus either by combustion or by means of nitric acid; wherefore this latter should always be employed in experiments of research.

Phosphorus is found in almost all animal substances, and in some plants which give a kind of animal analysis. In all these it is usually combined with charcoal, hydrogen, and azote, forming very compound radicals, which are, for the most part, in the state of oxyds by a first degree of union with oxygen. The discovery of Mr Hassenfratz, of phosphorus being contained in charcoal, gives reason to suspect that it is more common in the vegetable kingdom than has generally been supposed: It is certain, that, by proper processes, it may be procured from every individual of some of the families of plants.

As no experiment has hitherto given reason to suspect that phosphorus is a compound body, I have arranged it with the simple or elementary substances. It takes fire at the temperature of 32° (104°) of the thermometer.

Table of the Binary Combinations of Charcoal.

Simple Substances. Resulting Compounds.
{Oxyd of charcoal Unknown.
Oxygen {Carbonic acid Fixed air, chalky acid.
 
Sulphur Carburet of sulphur}
Phosphorus Carburet of phosphorus} Unknown.
Azote Carburet of azote}
 
{Carbono-hydrous radical
Hydrogen {Fixed and volatile oils
 
  {Of these only the carburets of
Metallic substances Carburets of metals {iron and zinc are known, and
  {were formerly called Plumbago.
 
Alkalies and earths Carburet of potash, &c. Unknown.

Sect. X.Observations upon Charcoal, and its Combinations with Simple Substances.

As charcoal has not been hitherto decomposed, it must, in the present state of our knowledge, be considered as a simple substance. By modern experiments it appears to exist ready formed in vegetables; and I have already remarked, that, in these, it is combined with hydrogen, sometimes with azote and phosphorus, forming compound radicals, which may be changed into oxyds or acids according to their degree of oxygenation.

To obtain the charcoal contained in vegetable or animal substances, we subject them to the action of fire, at first moderate, and afterwards very strong, on purpose to drive off the last portions of water, which adhere very obstinately to the charcoal. For chemical purposes, this is usually done in retorts of stone-ware or porcellain, into which the wood, or other matter, is introduced, and then placed in a reverberatory furnace, raised gradually to its greatest heat: The heat volatilizes, or changes into gas, all the parts of the body susceptible of combining with caloric into that form, and the charcoal, being more fixed in its nature, remains in the retort combined with a little earth and some fixed salts.

In the business of charring wood, this is done by a less expensive process. The wood is disposed in heaps, and covered with earth, so as to prevent the access of any more air than is absolutely necessary for supporting the fire, which is kept up till all the water and oil is driven off, after which the fire is extinguished by shutting up all the air-holes.

We may analyse charcoal either by combustion in air, or rather in oxygen gas, or by means of nitric acid. In either case we convert it into carbonic acid, and sometimes a little potash and some neutral salts remain. This analysis has hitherto been but little attended to by chemists; and we are not even certain if potash exists in charcoal before combustion, or whether it be formed by means of some unknown combination during that process.

Sect. XI.Observations upon the Muriatic, Fluoric, and Boracic Radicals, and their Combinations.

As the combinations of these substances, either with each other, or with the other combustible bodies, are hitherto entirely unknown, we have not attempted to form any table for their nomenclature. We only know that these radicals are susceptible of oxygenation, and of forming the muriatic, fluoric, and boracic acids, and that in the acid state they enter into a number of combinations, to be afterwards detailed. Chemistry has hitherto been unable to disoxygenate any of them, so as to produce them in a simple state. For this purpose, some substance must be employed to which oxygen has a stronger affinity than to their radicals, either by means of single affinity, or by double elective attraction. All that is known relative to the origin of the radicals of these acids will be mentioned in the sections set apart for considering their combinations with the salifiable bases.

Sect. XII.Observations upon the Combinations of Metals with each other.

Before closing our account of the simple or elementary substances, it might be supposed necessary to give a table of alloys or combinations of metals with each other; but, as such a table would be both exceedingly voluminous and very unsatisfactory, without going into a series of experiments not yet attempted, I have thought it adviseable to omit it altogether. All that is necessary to be mentioned is, that these alloys should be named according to the metal in largest proportion in the mixture or combination; thus the term alloy of gold and silver, or gold alloyed with silver, indicates that gold is the predominating metal.

Metallic alloys, like all other combinations, have a point of saturation. It would even appear, from the experiments of Mr de la Briche, that they have two perfectly distinct degrees of saturation.

Table of the Combinations of Azote in the state of Nitrous Acid with the Salifiable Bases, arranged according to the affinities of these Bases with the Acid.

Names of the bases. Names of the neutral salts.
New nomenclature. Notes.
Barytes Nitrite of barytes. These salts are only known of late, and have received no particular name in the old nomenclature.
Potash 〃potash.
Soda 〃soda.
Lime 〃lime.
Magnesia 〃magnesia.
Ammoniac 〃ammoniac.
Argill 〃argill.
 
Oxyd of zinc 〃zinc. As metals dissolve both in nitrous and nitric acids, metallic salts must of consequence be formed having different degrees of oxygenation. Those wherein the metal is least oxygenated must be called Nitrites, when more so, Nitrats; but the limits of this distinction are difficultly ascertainable. The older chemists were not acquainted with any of these salts.
〃 iron 〃iron.
〃 manganese 〃manganese.
〃 cobalt 〃cobalt.
〃 nickel 〃nickel.
〃 lead 〃lead.
〃 tin 〃tin.
〃 copper 〃copper.
〃 bismuth 〃bismuth.
〃 antimony 〃antimony.
〃 arsenic 〃arsenic.
〃 mercury 〃mercury.
〃 silver It is extremely probable that gold, silver and platina only form nitrats, and cannot subsist in the state of nitrites.
〃 gold
〃 platina

Table of the Combinations of Azote, completely saturated with Oxygen, in the state of Nitric Acid, with the Salifiable Bases, in the order of the affinity with the Acid.

Bases. Names of the resulting neutral salts.
New nomenclature. Old nomenclature.
Barytes Nitrat of barytes Nitre, with a base of heavy earth.
Potash 〃potash Nitre, saltpetre. Nitre with base of potash.
Soda 〃soda Quadrangular nitre. Nitre with base of mineral alkali.
Lime 〃lime Calcareous nitre. Nitre with calcareous base. Mother water of nitre, or saltpetre.
Magnesia 〃 magnesia Magnesian nitre. Nitre with base of magnesia.
Ammoniac 〃ammoniac Ammoniacal nitre.
Argill 〃argill Nitrous alum. Argillaceous nitre. Nitre with base of earth of alum.
Oxyd of zinc 〃zinc Nitre of zinc.
〃iron 〃iron Nitre of iron. Martial nitre. Nitrated iron.
〃manganese 〃manganese Nitre of manganese.
〃cobalt 〃cobalt Nitre of cobalt.
〃nickel 〃nickel Nitre of nickel.
〃lead 〃lead Saturnine nitre. Nitre of lead.
〃tin 〃tin Nitre of tin.
〃copper 〃copper Nitre of copper or of Venus.
〃bismuth 〃bismuth Nitre of bismuth.
〃antimony 〃antimony Nitre of antimony.
〃arsenic 〃arsenic Arsenical nitre.
〃mercury 〃mercury Mercurial nitre.
〃silver 〃silver Nitre of silver or luna. Lunar caustic.
〃gold 〃gold Nitre of gold.
〃platina 〃platina Nitre of platina.

Sect. XIII.Observations upon the Nitrous and Nitric Acids, and their Combinations.

The nitrous and nitric acids are procured from a neutral salt long known in the arts under the name of saltpetre. This salt is extracted by lixiviation from the rubbish of old buildings, from the earth of cellars, stables, or barns, and in general of all inhabited places. In these earths the nitric acid is usually combined with lime and magnesia, sometimes with potash, and rarely with argill. As all these salts, excepting the nitrat of potash, attract the moisture of the air, and consequently would be difficultly preserved, advantage is taken, in the manufactures of saltpetre and the royal refining house, of the greater affinity of the nitric acid to potash than these other bases, by which means the lime, magnesia, and argill, are precipitated, and all these nitrats are reduced to the nitrat of potash or saltpetre41.

The nitric acid is procured from this salt by distillation, from three parts of pure saltpetre decomposed by one part of concentrated sulphuric acid, in a retort with Woulfe's apparatus, (Pl. IV. fig. 1.) having its bottles half filled with water, and all its joints carefully luted. The nitrous acid passes over in form of red vapours surcharged with nitrous gas, or, in other words, not saturated with oxygen. Part of the acid condenses in the recipient in form of a dark orange red liquid, while the rest combines with the water in the bottles. During the distillation, a large quantity of oxygen gas escapes, owing to the greater affinity of oxygen to caloric, in a high temperature, than to nitrous acid, though in the usual temperature of the atmosphere this affinity is reversed. It is from the disengagement of oxygen that the nitric acid of the neutral salt is in this operation converted into nitrous acid. It is brought back to the state of nitric acid by heating over a gentle fire, which drives off the superabundant nitrous gas, and leaves the nitric acid much diluted with water.

Nitric acid is procurable in a more concentrated state, and with much less loss, by mixing very dry clay with saltpetre. This mixture is put into an earthern retort, and distilled with a strong fire. The clay combines with the potash, for which it has great affinity, and the nitric acid passes over, slightly impregnated with nitrous gas. This is easily disengaged by heating the acid gently in a retort, a small quantity of nitrous gas passes over into the recipient, and very pure concentrated nitric acid remains in the retort.

We have already seen that azote is the nitric radical. If to 20-1/2 parts, by weight, of azote 43-1/2 parts of oxygen be added, 64 parts of nitrous gas are formed; and, if to this we join 36 additional parts of oxygen, 100 parts of nitric acid result from the combination. Intermediate quantities of oxygen between these two extremes of oxygenation produce different species of nitrous acid, or, in other words, nitric acid less or more impregnated with nitrous gas. I ascertained the above proportions by means of decomposition; and, though I cannot answer for their absolute accuracy, they cannot be far removed from truth. Mr Cavendish, who first showed by synthetic experiments that azote is the base of nitric acid, gives the proportions of azote a little larger than I have done; but, as it is not improbable that he produced the nitrous acid and not the nitric, that circumstance explains in some degree the difference in the results of our experiments.

As, in all experiments of a philosophical nature, the utmost possible degree of accuracy is required, we must procure the nitric acid for experimental purposes, from nitre which has been previously purified from all foreign matter. If, after distillation, any sulphuric acid is suspected in the nitric acid, it is easily separated by dropping in a little nitrat of barytes, so long as any precipitation takes place; the sulphuric acid, from its greater affinity, attracts the barytes, and forms with it an insoluble neutral salt, which falls to the bottom. It may be purified in the same manner from muriatic acid, by dropping in a little nitrat of silver so long as any precipitation of muriat of silver is produced. When these two precipitations are finished, distill off about seven-eighths of the acid by a gentle heat, and what comes over is in the most perfect degree of purity.

The nitric acid is one of the most prone to combination, and is at the same time very easily decomposed. Almost all the simple substances, with the exception of gold, silver, and platina, rob it less or more of its oxygen; some of them even decompose it altogether. It was very anciently known, and its combinations have been more studied by chemists than those of any other acid. These combinations were named nitres by Messrs Macquer and Beaumé; but we have changed their names to nitrats and nitrites, according as they are formed by nitric or by nitrous acid, and have added the specific name of each particular base, to distinguish the several combinations from each other.

41 Saltpetre is likewise procured in large quantities by lixiviating the natural soil in some parts of Bengal, and of the Russian Ukrain. — E.

Table of the Combinations of Sulphuric Acid with the Salifiable Bases, in the order of affinity.

Names of the bases. Resulting compounds.
  New nomenclature. Old nomenclature.
Barytes   Sulphat of barytes Heavy spar. Vitriol of heavy earth.
Potash     potash Vitriolated tartar. Sal de duobus. Arcanum duplicatam.
Soda     soda Glauber's salt.
Lime     lime Selenite, gypsum, calcareous vitriol.
Magnesia     magnesia Epsom salt, sedlitz salt, magnesian vitriol.
Ammoniac     ammoniac Glauber's secret sal ammoniac.
Argill     argill Alum.
Oxyd of zinc   zinc White vitriol, goslar vitriol, white coperas, vitriol of zinc.
iron   iron Green coperas, green vitriol, martial vitriol, vitriol of iron.
manganese   manganese Vitriol of manganese.
cobalt   cobalt Vitriol of cobalt.
nickel   nickel Vitriol of nickel.
lead   lead Vitriol of lead.
tin   tin Vitriol of tin.
copper   copper Blue coperas, blue vitriol, Roman vitriol, vitriol of copper.
bismuth   bismuth Vitriol of bismuth.
antimony   antimony Vitriol of antimony.
arsenic   arsenic Vitriol of arsenic.
mercury   mercury Vitriol of mercury.
silver   silver Vitriol of silver.
gold   gold Vitriol of gold.
platina   platina Vitriol of platina.

Sect. XIV.Observations upon Sulphuric Acid and its Combinations.

For a long time this acid was procured by distillation from sulphat of iron, in which sulphuric acid and oxyd of iron are combined, according to the process described by Basil Valentine in the fifteenth century; but, in modern times, it is procured more oeconomically by the combustion of sulphur in proper vessels. Both to facilitate the combustion, and to assist the oxygenation of the sulphur, a little powdered saltpetre, nitrat of potash, is mixed with it; the nitre is decomposed, and gives out its oxygen to the sulphur, which contributes to its conversion into acid. Notwithstanding this addition, the sulphur will only continue to burn in close vessels for a limited time; the combination ceases, because the oxygen is exhausted, and the air of the vessels reduced almost to pure azotic gas, and because the acid itself remains long in the state of vapour, and hinders the progress of combustion.

In the manufactories for making sulphuric acid in the large way, the mixture of nitre and sulphur is burnt in large close built chambers lined with lead, having a little water at the bottom for facilitating the condensation of the vapours. Afterwards, by distillation in large retorts with a gentle heat, the water passes over, slightly impregnated with acid, and the sulphuric acid remains behind in a concentrated state. It is then pellucid, without any flavour, and nearly double the weight of an equal bulk of water. This process would be greatly facilitated, and the combustion much prolonged, by introducing fresh air into the chambers, by means of several pairs of bellows directed towards the flame of the sulphur, and by allowing the nitrous gas to escape through long serpentine canals, in contact with water, to absorb any sulphuric or sulphurous acid gas it might contain.

By one experiment, Mr Berthollet found that 69 parts of sulphur in combustion, united with 31 parts of oxygen, to form 100 parts of sulphuric acid; and, by another experiment, made in a different manner, he calculates that 100 parts of sulphuric acid consists of 72 parts sulphur, combined with 28 parts of oxygen, all by weight.

This acid, in common with every other, can only dissolve metals when they have been previously oxydated; but most of the metals are capable of decomposing a part of the acid, so as to carry off a sufficient quantity of oxygen, to render themselves soluble in the part of the acid which remains undecomposed. This happens with silver, mercury, iron, and zinc, in boiling concentrated sulphuric acid; they become first oxydated by decomposing part of the acid, and then dissolve in the other part; but they do not sufficiently disoxygenate the decomposed part of the acid to reconvert it into sulphur; it is only reduced to the state of sulphurous acid, which, being volatilised by the heat, flies off in form of sulphurous acid gas.

Silver, mercury, and all the other metals except iron and zinc, are insoluble in diluted sulphuric acid, because they have not sufficient affinity with oxygen to draw it off from its combination either with the sulphur, the sulphurous acid, or the hydrogen; but iron and zinc, being assisted by the action of the acid, decompose the water, and become oxydated at its expence, without the help of heat.

Table of the Combinations of the Sulphurous Acid with the Salifiable Bases, in the order of affinity.

Names of the Bases. Names of the Neutral Salts.
Barytes Sulphite of barytes.
Potash     potash.
Soda     soda.
Lime     lime.
Magnesia     magnesia.
Ammoniac     ammoniac.
Argill     argill.
Oxyd of zinc   zinc.
iron   iron.
manganese   manganese.
cobalt   cobalt.
nickel   nickel.
lead   lead.
tin   tin.
copper   copper.
bismuth   bismuth.
antimony   antimony.
arsenic   arsenic.
mercury   mercury.
silver   silver.
gold   gold.
platina   platina.

Note.— The only one of these salts known to the old chemists was the sulphite of potash, under the name of Stahl's sulphureous salt. So that, before our new nomenclature, these compounds must have been named Stahl's sulphureous salt, having base of fixed vegetable alkali, and so of the rest.

In this Table we have followed Bergman's order of affinity of the sulphuric acid, which is the same in regard to the earths and alkalies, but it is not certain if the order be the same for the metallic oxyds. — A.

Sect. XV.Observations upon Sulphurous Acid, and its Combinations.

The sulphurous acid is formed by the union of oxygen with sulphur by a lesser degree of oxygenation than the sulphuric acid. It is procurable either by burning sulphur slowly, or by distilling sulphuric acid from silver, antimony, lead, mercury, or charcoal; by which operation a part of the oxygen quits the acid, and unites to these oxydable bases, and the acid passes over in the sulphurous state of oxygenation. This acid, in the common pressure and temperature of the air, can only exist in form of gas; but it appears, from the experiments of Mr Clouet, that, in a very low temperature, it condenses, and becomes fluid. Water absorbs a great deal more of this gas than of carbonic acid gas, but much less than it does of muriatic acid gas.

That the metals cannot be dissolved in acids without being previously oxydated, or by procuring oxygen, for that purpose, from the acids during solution, is a general and well established fact, which I have perhaps repeated too often. Hence, as sulphurous acid is already deprived of great part of the oxygen necessary for forming the sulphuric acid, it is more disposed to recover oxygen, than to furnish it to the greatest part of the metals; and, for this reason, it cannot dissolve them, unless previously oxydated by other means. From the same principle it is that the metallic oxyds dissolve without effervescence, and with great facility, in sulphurous acid. This acid, like the muriatic, has even the property of dissolving metallic oxyds surcharged with oxygen, and consequently insoluble in sulphuric acid, and in this way forms true sulphats. Hence we might be led to conclude that there are no metallic sulphites, were it not that the phenomena which accompany the solution of iron, mercury, and some other metals, convince us that these metallic substances are susceptible of two degrees of oxydation, during their solution in acids. Hence the neutral salt in which the metal is least oxydated must be named sulphite, and that in which it is fully oxydated must be called sulphat. It is yet unknown whether this distinction is applicable to any of the metallic sulphats, except those of iron and mercury.

Table of the Combinations of Phosphorous and Phosphoric Acids, with the Salifiable Bases, in the Order of Affinity.

Names of the Bases. Names of the Neutral Salts formed by
Phosphorous Acid, Phosphoric Acid.
Phosphites of(B) Phosphats of(C)
Lime lime lime.
Barytes barytes barytes.
Magnesia magnesia magnesia.
Potash potash potash.
Soda soda soda.
Ammoniac ammoniac ammoniac.
Argill argill argill.
Oxyds of(A)
zinc zinc zinc.
iron iron iron.
manganese manganese manganese.
cobalt cobalt cobalt.
nickel nickel nickel.
lead lead lead.
tin tin tin.
copper copper copper.
bismuth bismuth bismuth.
antimony antimony antimony.
arsenic arsenic arsenic.
mercury mercury mercury.
silver silver silver.
gold gold gold.
platina platina platina.

[Note A: The existence of metallic phosphites supposes that metals are susceptible of solution in phosphoric acid at different degrees of oxygenation, which is not yet ascertained. — A.]

[Note B: All the phosphites were unknown till lately, and consequently have not hitherto received names. — A.]

[Note C: The greater part of the phosphats were only discovered of late, and have not yet been named. — A.]

Sect. XVI. —Observations upon Phosphorous and Phosphoric Acids, and their Combinations.

Under the article Phosphorus, Part II. Sect. X. we have already given a history of the discovery of that singular substance, with some observations upon the mode of its existence in vegetable and animal bodies. The best method of obtaining this acid in a state of purity is by burning well purified phosphorus under bell-glasses, moistened on the inside with distilled water; during combustion it absorbs twice and a half its weight of oxygen; so that 100 parts of phosphoric acid is composed of 28-1/2 parts of phosphorus united to 71-1/2 parts of oxygen. This acid may be obtained concrete, in form of white flakes, which greedily attract the moisture of the air, by burning phosphorus in a dry glass over mercury.

To obtain phosphorous acid, which is phosphorus less oxygenated than in the state of phosphoric acid, the phosphorus must be burnt by a very slow spontaneous combustion over a glass-funnel leading into a crystal phial; after a few days, the phosphorus is found oxygenated, and the phosphorous acid, in proportion as it forms, has attracted moisture from the air, and dropped into the phial. The phosphorous acid is readily changed into phosphoric acid by exposure for a long time to the free air; it absorbs oxygen from the air, and becomes fully oxygenated.

As phosphorus has a sufficient affinity for oxygen to attract it from the nitric and muriatic acids, we may form phosphoric acid, by means of these acids, in a very simple and cheap manner. Fill a tubulated receiver, half full of concentrated nitric acid, and heat it gently, then throw in small pieces of phosphorus through the tube, these are dissolved with effervescence and red fumes of nitrous gas fly off; add phosphorus so long as it will dissolve, and then increase the fire under the retort to drive off the last particles of nitric acid; phosphoric acid, partly fluid and partly concrete, remains in the retort.

Table of the Combinations of Carbonic Acid, with the Salifiable Bases, in the Order of Affinity.

Names of Bases Resulting Neutral Salts.
New Nomenclature. Old Nomenclature.
Barytes Carbonates of barytes(A) Aërated or effervescent heavy earth.
Lime   lime Chalk, calcareous spar, Aërated calcareous earth.
Potash   potash Effervescing or aërated fixed vegetable alkali, mephitis of potash.
Soda   soda Aërated or effervescing fixed mineral alkali, mephitic soda.
Magnesia   magnesia Aërated, effervescing, mild, or mephitic magnesia.
Ammoniac   ammoniac Aërated, effervescing, mild, or mephitic volatile alkali.
Argill   argill Aërated or effervescing argillaceous earth, or earth of alum.
Oxyds of
zinc   zinc Zinc spar, mephitic or aërated zinc.
iron   iron Sparry iron-ore, mephitic or aërated iron.
manganese   manganese Aërated manganese.
cobalt   cobalt Aërated cobalt.
nickel   nickel Aërated nickel.
lead   lead Sparry lead-ore, or aërated lead.
tin   tin Aërated tin.
copper   copper Aërated copper.
bismuth   bismuth Aërated bismuth.
antimony   antimony Aërated antimony.
arsenic   arsenic Aërated arsenic.
mercury   mercury Aërated mercury.
silver   silver Aërated silver.
gold   gold Aërated gold.
platina   platina Aërated platina.

[Note A: As these salts have only been understood of late, they have not, properly speaking, any old names. Mr Morveau, in the First Volume of the Encyclopedia, calls them Mephites; Mr Bergman gives them the name of aërated; and Mr de Fourcroy, who calls the carbonic acid chalky acid, gives them the name of chalks. — A]

Sect. XVII. —Observations upon Carbonic Acid, and its Combinations.

Of all the known acids, the carbonic is the most abundant in nature; it exists ready formed in chalk, marble, and all the calcareous stones, in which it is neutralized by a particular earth called lime. To disengage it from this combination, nothing more is requisite than to add some sulphuric acid, or any other which has a stronger affinity for lime; a brisk effervescence ensues, which is produced by the disengagement of the carbonic acid which assumes the state of gas immediately upon being set free. This gas, incapable of being condensed into the solid or liquid form by any degree of cold or of pressure hitherto known, unites to about its own bulk of water, and thereby forms a very weak acid. It may likewise be obtained in great abundance from saccharine matter in fermentation, but is then contaminated by a small portion of alkohol which it holds in solution.

As charcoal is the radical of this acid, we may form it artificially, by burning charcoal in oxygen gas, or by combining charcoal and metallic oxyds in proper proportions; the oxygen of the oxyd combines with the charcoal, forming carbonic acid gas, and the metal being left free, recovers its metallic or reguline form.

We are indebted for our first knowledge of this acid to Dr Black, before whose time its property of remaining always in the state of gas had made it to elude the researches of chemistry.

It would be a most valuable discovery to society, if we could decompose this gas by any cheap process, as by that means we might obtain, for economical purposes, the immense store of charcoal contained in calcareous earths, marbles, limestones, &c. This cannot be effected by single affinity, because, to decompose the carbonic acid, it requires a substance as combustible as charcoal itself, so that we should only make an exchange of one combustible body for another not more valuable; but it may possibly be accomplished by double affinity, since this process is so readily performed by Nature, during vegetation, from the most common materials.

Table of the Combinations of Muriatic Acid, with the Salifiable Bases, in the Order of Affinity.

Names of the bases. Resulting Neutral Salts.
New nomenclature. Old nomenclature.
Barytes. Muriat of
barytes Sea-salt, having base of heavy earth.
Potash potash Febrifuge salt of Sylvius: Muriated vegetable fixed alkali.
Soda soda Sea-salt.
Lime lime Muriated lime. Oil of lime.
Magnesia magnesia Marine Epsom salt. Muriated magnesia.
Ammoniac ammoniac Sal ammoniac.
Argill argill {Muriated alum, sea-salt with base of earth of alum.
Oxyd of
zinc zinc Sea-salt of, or muriatic zinc.
iron iron Salt of iron, Martial sea-salt.
manganese manganese Sea-salt of manganese.
cobalt cobalt Sea-salt of cobalt.
nickel nickel Sea-salt of nickel.
lead lead Horny-lead. Plumbum corneum.
tin smoaking of tin solid of tin Smoaking liquor of Libavius. Solid butter of tin.
copper copper Sea-salt of copper.
bismuth bismuth Sea-salt of bismuth.
antimony antimony Sea-salt of antimony.
arsenic arsenic Sea-salt of arsenic.
mercury {sweet of mercury Sweet sublimate of mercury, calomel, aquila alba.
{corrosive of mercury Corrosive sublimate of mercury.
silver silver Horny silver, argentum corneum, luna cornea.
gold gold Sea-salt of gold.
platina platina Sea-salt of platina.

Table Of the Combinations of Oxygenated Muriatic Acid, with the Salifiable Bases, in the Order of Affinity.

Names of the Bases. Names of the Neutral Salts by the new Nomenclature.
Oxygenated muriat of
Barytes barytes.
Potash potash.
Soda soda.
Lime lime.
Magnesia magnesia.
Argill argill.
Oxyd of
zinc zinc.
iron iron.
manganese manganese.
cobalt cobalt.
nickel nickel.
lead lead.
tin tin.
copper copper.
bismuth bismuth.
antimony antimony.
arsenic arsenic.
mercury mercury.
silver silver.
gold gold.
platina platina.

This order of salts, entirely unknown to the ancient chemists, was discovered in 1786 by Mr Berthollet. — A.

Sect. XIX. —Observations upon Muriatic and Oxygenated Muriatic Acids, and their Combinations.

Muriatic acid is very abundant in the mineral kingdom naturally combined with different salifiable bases, especially with soda, lime, and magnesia. In sea-water, and the water of several lakes, it is combined with these three bases, and in mines of rock-salt it is chiefly united to soda. This acid does not appear to have been hitherto decomposed in any chemical experiment; so that we have no idea whatever of the nature of its radical, and only conclude, from analogy with the other acids, that it contains oxygen as its acidifying principle. Mr Berthollet suspects the radical to be of a metallic nature; but, as Nature appears to form this acid daily, in inhabited places, by combining miasmata with aëriform fluids, this must necessarily suppose a metallic gas to exist in the atmosphere, which is certainly not impossible, but cannot be admitted without proof.

The muriatic acid has only a moderate adherence to the salifiable bases, and can readily be driven from its combination with these by sulphuric acid. Other acids, as the nitric, for instance, may answer the same purpose; but nitric acid being volatile, would mix, during distillation, with the muriatic. About one part of sulphuric acid is sufficient to decompose two parts of decrepitated sea-salt. This operation is performed in a tubulated retort, having Woulfe's apparatus, (Pl. IV. Fig. 1.), adapted to it. When all the junctures are properly lured, the sea-salt is put into the retort through the tube, the sulphuric acid is poured on, and the opening immediately closed with its ground crystal stopper. As the muriatic acid can only subsist in the gaseous form in the ordinary temperature, we could not condense it without the presence of water. Hence the use of the water with which the bottles in Woulfe's apparatus are half filled; the muriatic acid gas, driven off from the sea-salt in the retort, combines with the water, and forms what the old chemists called smoaking spirit of salt, or Glauber's spirit of sea-salt, which we now name muriatic acid.

The acid obtained by the above process is still capable of combining with a farther dose of oxygen, by being distilled from the oxyds of manganese, lead, or mercury, and the resulting acid, which we name oxygenated muriatic acid, can only, like the former, exist in the gasseous form, and is absorbed, in a much smaller quantity by water. When the impregnation of water with this gas is pushed beyond a certain point, the superabundant acid precipitates to the bottom of the vessels in a concrete form. Mr Berthollet has shown that this acid is capable of combining with a great number of the salifiable bases; the neutral salts which result from this union are susceptible of deflagrating with charcoal, and many of the metallic substances; these deflagrations are very violent and dangerous, owing to the great quantity of caloric which the oxygen carries alongst with it into the composition of oxygenated muriatic acid.

Table of the Combinations of Nitro-muriatic Acid with the Salifiable Bases, in the Order of Affinity, so far as is known.

Names of the Bases. Names of the Neutral Salts.
Argill   Nitro-muriat of argill.
Ammoniac     ammoniac.
Oxyd of
antimony   antimony.
silver   silver.
arsenic   arsenic.
Barytes     barytes.
Oxyd of bismuth   bismuth.
Lime     lime.
Oxyd of
cobalt   cobalt.
copper   copper.
tin   tin.
iron   iron.
Magnesia     magnesia.
Oxyd of
manganese   manganese.
mercury   mercury.
molybdena   molybdena.
nickel   nickel.
gold   gold.
platina   platina.
lead   lead.
Potash     potash.
Soda     soda.
Oxyd of
tungstein   tungstein.
zinc   zinc.

Note.— Most of these combinations, especially those with the earths and alkalies, have been little examined, and we are yet to learn whether they form a mixed salt in which the compound radical remains combined, or if the two acids separate, to form two distinct neutral salts. — A.

Sect. XX.Observations upon the Nitro-Muriatic Acid, and its Combinations.

The nitro-muriatic acid, formerly called aqua regia, is formed by a mixture of nitric and muriatic acids; the radicals of these two acids combine together, and form a compound base, from which an acid is produced, having properties peculiar to itself, and distinct from those of all other acids, especially the property of dissolving gold and platina.

In dissolutions of metals in this acid, as in all other acids, the metals are first oxydated by attracting a part of the oxygen from the compound radical. This occasions a disengagement of a particular species of gas not hitherto described, which may be called nitro-muriatic gas; it has a very disagreeable smell, and is fatal to animal life when respired; it attacks iron, and causes it to rust; it is absorbed in considerable quantity by water, which thereby acquires some slight characters of acidity. I had occasion to make these remarks during a course of experiments upon platina, in which I dissolved a considerable quantity of that metal in nitro-muriatic acid.

I at first suspected that, in the mixture of nitric and muriatic acids, the latter attracted a part of the oxygen from the former, and became converted into oxygenated muriatic acid, which gave it the property of dissolving gold; but several facts remain inexplicable upon this supposition. Were it so, we must be able to disengage nitrous gas by heating this acid, which however does not sensibly happen. From these considerations, I am led to adopt the opinion of Mr Berthollet, and to consider nitro-muriatic acid as a single acid, with a compound base or radical.

Table of the Combinations of Fluoric Acid, with the Salifiable Bases, in the Order of Affinity.

Names of the Bases. Names of the Neutral Salts.
Lime Fluat of lime.
Barytes     barytes.
Magnesia     magnesia.
Potash     potash.
Soda     soda.
Ammoniac     ammoniac.
Oxyd of
zinc   zinc.
manganese   manganese.
iron   iron.
lead   lead.
tin   tin.
cobalt   cobalt.
copper   copper.
nickel   nickel.
arsenic   arsenic.
bismuth   bismuth.
mercury   mercury.
silver   silver.
gold   gold.
platina   platina.
And by the dry way,
Argill   Fluat of argill.

Note.— These combinations were entirely unknown to the old chemists, and consequently have no names in the old nomenclature. — A.

Sect. XXI. —Observations upon the Fluoric Acid, and its Combinations.

Fluoric exists ready formed by Nature in the fluoric spars42, combined with calcareous earth, so as to form an insoluble neutral salt. To obtain it disengaged from that combination, fluor spar, or fluat of lime, is put into a leaden retort, with a proper quantity of sulphuric acid, a recipient likewise of lead, half full of water, is adapted, and fire is applied to the retort. The sulphuric acid, from its greater affinity, expels the fluoric acid which passes over and is absorbed by the water in the receiver. As fluoric acid is naturally in the gasseous form in the ordinary temperature, we can receive it in a pneumato-chemical apparatus over mercury. We are obliged to employ metallic vessels in this process, because fluoric acid dissolves glass and silicious earth, and even renders these bodies volatile, carrying them over with itself in distillation in the gasseous form.

We are indebted to Mr Margraff for our first acquaintance with this acid, though, as he could never procure it free from combination with a considerable quantity of silicious earth, he was ignorant of its being an acid sui generis. The Duke de Liancourt, under the name of Mr Boulanger, considerably increased our knowledge of its properties; and Mr Scheele seems to have exhausted the subject. The only thing remaining is to endeavour to discover the nature of the fluoric radical, of which we cannot hitherto form any ideas, as the acid does not appear to have been decomposed in any experiment. It is only by means of compound affinity that experiments ought to be made with this view, with any probability of success.

42 Commonly called Derbyshire spars. — E.

Table of the Combinations of Boracic Acid, with the Salifiable Bases, in the Order of Affinity.

Bases. Neutral Salts.
Lime   Borat of lime.
Barytes     barytes.
Magnesia     magnesia.
Potash     potash.
Soda     soda.
Ammoniac     ammoniac.
Oxyd of
zinc   zinc.
iron   iron.
lead   lead.
tin   tin.
cobalt   cobalt.
copper   copper.
nickel   nickel.
mercury   mercury.
Argill     argill.

Note.— Most of these combinations were neither known nor named by the old chemists. The boracic acid was formerly called sedative salt, and its compounds borax, with base of fixed vegetable alkali, &c. — A.

Sect. XXII. —Observations upon Boracic Add and its Combinations.

This is a concrete acid, extracted from a salt procured from India called borax or tincall. Although borax has been very long employed in the arts, we have as yet very imperfect knowledge of its origin, and of the methods by which it is extracted and purified; there is reason to believe it to be a native salt, found in the earth in certain parts of the east, and in the water of some lakes. The whole trade of borax is in the hands of the Dutch, who have been exclusively possessed of the art of purifying it till very lately, that Messrs L'Eguillier of Paris have rivalled them in the manufacture; but the process still remains a secret to the world.

By chemical analysis we learn that borax is a neutral salt with excess of base, consisting of soda, partly saturated with a peculiar acid long called Homberg's sedative salt, now the boracic acid. This acid is found in an uncombined state in the waters of certain lakes. That of Cherchiais in Italy contains 94-1/2 grains in each pint of water.

To obtain boracic acid, dissolve some borax in boiling water, filtrate the solution, and add sulphuric acid, or any other having greater affinity to soda than the boracic acid; this latter acid is separated, and is procured in a crystalline form by cooling. This acid was long considered as being formed during the process by which it is obtained, and was consequently supposed to differ according to the nature of the acid employed in separating it from the soda; but it is now universally acknowledged that it is identically the same acid, in whatever way procured, provided it be properly purified from mixture of other acids, by warning, and by repeated solution and cristallization. It is soluble both in water and alkohol, and has the property of communicating a green colour to the flame of that spirit. This circumstance led to a suspicion of its containing copper, which is not confirmed by any decisive experiment. On the contrary, if it contain any of that metal, it must only be considered as an accidental mixture. It combines with the salifiable bases in the humid way; and though, in this manner, it is incapable of dissolving any of the metals directly, this combination is readily affected by compound affinity.

The Table presents its combinations in the order of affinity in the humid way; but there is a considerable change in the order when we operate via sicca; for, in that case, argill, though the last in our list, must be placed immediately after soda.

The boracic radical is hitherto unknown; no experiments having as yet been able to decompose the acid; We conclude, from analogy with the other acids, that oxygen exists in its composition as the acidifying principle.

Table of the Combinations of Arseniac Acid, with the Salifiable Bases, in the Order of Affinity.

Bases. Neutral Salts.
Lime   Arseniat of lime.
Barytes     barytes.
Magnesia     magnesia.
Potash     potash.
Soda     soda.
Ammoniac     ammoniac.
Oxyd of
zinc   zinc.
manganese   manganese.
iron   iron.
lead   lead.
tin   tin.
cobalt   cobalt.
copper   copper.
nickel   nickel.
bismuth   bismuth.
mercury   mercury.
antimony   antimony.
silver   silver.
gold   gold.
platina   platina.
Argill     argill.

Note.— This order of salts was entirely unknown to the antient chemists. Mr Macquer, in 1746, discovered the combinations of arseniac acid with potash and soda, to which he gave the name of arsenical neutral salts. — A.

Sect. XXIII. —Observations upon Arseniac Acid, and its Combinations.

In the Collections of the Academy for 1746, Mr Macquer shows that, when a mixture of white oxyd of arsenic and nitre are subjected to the action of a strong fire, a neutral salt is obtained, which he calls neutral salt of arsenic. At that time, the cause of this singular phenomenon, in which a metal acts the part of an acid, was quite unknown; but more modern experiments teach that, during this process, the arsenic becomes oxygenated, by carrying off the oxygen of the nitric acid; it is thus converted into a real acid, and combines with the potash. There are other methods now known for oxygenating arsenic, and obtaining its acid free from combination. The most simple and most effectual of these is as follows: Dissolve white oxyd of arsenic in three parts, by weight, of muriatic acid; to this solution, in a boiling state, add two parts of nitric acid, and evaporate to dryness. In this process the nitric acid is decomposed, its oxygen unites with the oxyd of arsenic, and converts it into an acid, and the nitrous radical flies off in the state of nitrous gas; whilst the muriatic acid is converted by the heat into muriatic acid gas, and may be collected in proper vessels. The arseniac acid is entirely freed from the other acids employed during the process by heating it in a crucible till it begins to grow red; what remains is pure concrete arseniac acid.

Mr Scheele's process, which was repeated with great success by Mr Morveau, in the laboratory at Dijon, is as follows: Distil muriatic acid from the black oxyd of manganese, this converts it into oxygenated muriatic acid, by carrying off the oxygen from the manganese, receive this in a recipient containing white oxyd of arsenic, covered by a little distilled water; the arsenic decomposes the oxygenated muriatic acid, by carrying off its supersaturation of oxygen, the arsenic is converted into arseniac acid, and the oxygenated muriatic acid is brought back to the state of common muriatic acid. The two acids are separated by distillation, with a gentle heat increased towards the end of the operation, the muriatic acid passes over, and the arseniac acid remains behind in a white concrete form.

The arseniac acid is considerably less volatile than white oxyd of arsenic; it often contains white oxyd of arsenic in solution, owing to its not being sufficiently oxygenated; this is prevented by continuing to add nitrous acid, as in the former process, till no more nitrous gas is produced. From all these observations I would give the following definition of arseniac acid. It is a white concrete metallic acid, formed by the combination of arsenic with oxygen, fixed in a red heat, soluble in water, and capable of combining with many of the salifiable bases.

Sect. XXIV.Observations upon Molybdic Acid, and its Combinations with Acidifiable Bases43.

Molybdena is a particular metallic body, capable of being oxygenated, so far as to become a true concrete acid44. For this purpose, one part ore of molybdena, which is a natural sulphuret of that metal, is put into a retort, with five or six parts nitric acid, diluted with a quarter of its weight of water, and heat is applied to the retort; the oxygen of the nitric acid acts both upon the molybdena and the sulphur, converting the one into molybdic, and the other into sulphuric acid; pour on fresh quantities of nitric acid so long as any red fumes of nitrous gas escape; the molydbena is then oxygenated as far as is possible, and is found at the bottom of the retort in a pulverulent form, resembling chalk. It must be washed in warm water, to separate any adhering particles of sulphuric acid; and, as it is hardly soluble, we lose very little of it in this operation. All its combinations with salifiable bases were unknown to the ancient chemists.

43 I have not added the Table of these combinations, as the order of their affinity is entirely unknown; they are called molybdats of argil, antimony, potash, &c. — E.

44 This acid was discovered by Mr Scheele, to whom chemistry is indebted for the discovery of several other acids. — A.

Table of the Combinations of Tungstic Acid with the Salifiable Bases.

Bases. Neutral Salts.
Lime Tungstat of lime.
Barytes   barytes.
Magnesia   magnesia.
Potash   potash.
Soda   soda.
Ammoniac   ammoniac.
Argill   argill.
Oxyd of antimony(A), &c.   antimony(B), &c.

[Note A: The combinations with metallic oxyds were set down by Mr Lavoisier in alphabetical order; their order of affinity being unknown, I have omitted them, as serving no purpose. — E.]

[Note B: All these salts were unknown to the ancient chemists. — A.]

Sect. XXV.Observations upon Tungstic Acid, and its Combinations.

Tungstein is a particular metal, the ore of which has frequently been confounded with that of tin. The specific gravity of this ore is to water as 6 to 1; in its form of cristallization it resembles the garnet, and varies in colour from a pearl-white to yellow and reddish; it is found in several parts of Saxony and Bohemia. The mineral called Wolfram, which is frequent in the mines of Cornwal, is likewise an ore of this metal. In all these ores the metal is oxydated; and, in some of them, it appears even to be oxygenated to the state of acid, being combined with lime into a true tungstat of lime.

To obtain the acid free, mix one part of ore of tungstein with four parts of carbonat of potash, and melt the mixture in a crucible, then powder and pour on twelve parts of boiling water, add nitric acid, and the tungstic acid precipitates in a concrete form. Afterwards, to insure the complete oxygenation of the metal, add more nitric acid, and evaporate to dryness, repeating this operation so long as red fumes of nitrous gas are produced. To procure tungstic acid perfectly pure, the fusion of the ore with carbonat of potash must be made in a crucible of platina, otherwise the earth of the common crucibles will mix with the products, and adulterate the acid.

Table of the Combinations of Tartarous Acid, with the Salifiable Bases, in the Order of Affinity.

Bases. Neutral Salts.
Lime   Tartarite of lime.
Barytes     barytes.
Magnesia     magnesia.
Potash     potash.
Soda     soda.
Ammoniac     ammoniac.
Argill     argill.
Oxyd of
zinc   zinc.
iron   iron.
manganese   manganese.
cobalt   cobalt.
nickel   nickel.
lead   lead.
tin   tin.
copper   copper.
bismuth   bismuth.
antimony   antimony.
arsenic   arsenic.
silver   silver.
mercury   mercury.
gold   gold.
platina   platina.

Sect. XXVI.Observations upon Tartarous Acid, and its Combinations.

Tartar, or the concretion which fixes to the inside of vessels in which the fermentation of wine is completed, is a well known salt, composed of a peculiar acid, united in considerable excess to potash. Mr Scheele first pointed out the method of obtaining this acid pure. Having observed that it has a greater affinity to lime than to potash, he directs us to proceed in the following manner. Dissolve purified tartar in boiling water, and add a sufficient quantity of lime till the acid be completely saturated. The tartarite of lime which is formed, being almost insoluble in cold water, falls to the bottom, and is separated from the solution of potash by decantation; it is afterwards washed in cold water, and dried; then pour on some sulphuric acid, diluted with eight or nine parts of water, digest for twelve hours in a gentle heat, frequently stirring the mixture; the sulphuric acid combines with the lime, and the tartarous acid is left free. A small quantity of gas, not hitherto examined, is disengaged during this process. At the end of twelve hours, having decanted off the clear liquor, wash the sulphat of lime in cold water, which add to the decanted liquor, then evaporate the whole, and the tartarous acid is obtained in a concrete form. Two pounds of purified tartar, by means of from eight to ten ounces of sulphuric acid, yield about eleven ounces of tartarous acid.

As the combustible radical exists in excess, or as the acid from tartar is not fully saturated with oxygen, we call it tartarous acid, and the neutral salts formed by its combinations with salifiable bases tartarites. The base of the tartarous acid is a carbono-hydrous or hydro-carbonous radical, less oxygenated than in the oxalic acid; and it would appear, from the experiments of Mr Hassenfratz, that azote enters into the composition of the tartarous radical, even in considerable quantity. By oxygenating the tartarous acid, it is convertible into oxalic, malic, and acetous acids; but it is probable the proportions of hydrogen and charcoal in the radical are changed during these conversions, and that the difference between these acids does not alone consist in the different degrees of oxygenation.

The tartarous acid is susceptible of two degrees of saturation in its combinations with the fixed alkalies; by one of these a salt is formed with excess of acid, improperly called cream of tartar, which in our new nomenclature is named acidulous tartarite of potash; by a second or equal degree of saturation a perfectly neutral salt is formed, formerly called vegetable salt, which we name tartarite of potash. With soda this acid forms tartarite of soda, formerly called sal de Seignette, or sal polychrest of Rochell.

Sect. XXVII.Observations upon Malic Acid, and its Combinations with the Salifiable Bases45.

The malic acid exists ready formed in the sour juice of ripe and unripe apples, and many other fruits, and is obtained as follows: Saturate the juice of apples with potash or soda, and add a proper proportion of acetite of lead dissolved in water; a double decomposition takes place, the malic acid combines with the oxyd of lead and precipitates, being almost insoluble, and the acetite of potash or soda remains in the liquor. The malat of lead being separated by decantation, is washed with cold water, and some dilute sulphuric acid is added; this unites with the lead into an insoluble sulphat, and the malic acid remains free in the liquor.

This acid, which is found mixed with citric and tartarous acid in a great number of fruits, is a kind of medium between oxalic and acetous acids being more oxygenated than the former, and less so than the latter. From this circumstance, Mr Hermbstadt calls it imperfect vinegar; but it differs likewise from acetous acid, by having rather more charcoal, and less hydrogen, in the composition of its radical.

When an acid much diluted has been used in the foregoing process, the liquor contains oxalic as well as malic acid, and probably a little tartarous, these are separated by mixing lime-water with the acids, oxalat, tartarite, and malat of lime are produced; the two former, being insoluble, are precipitated, and the malat of lime remains dissolved; from this the pure malic acid is separated by the acetite of lead, and afterwards by sulphuric acid, as directed above.

45 I have omitted the Table, as the order of affinity is unknown, and is given by Mr Lavoisier only in alphabetical order. All the combinations of malic acid with salifiable bases, which are named malats, were unknown to the ancient chemists. — E.

Table of the Combinations of Citric Acid, with the Salifiable Bases, in the Order of Affinity(A).

Bases. Neutral Salts.
Barytes   Citrat of barytes.
Lime     lime.
Magnesia     magnesia.
Potash     potash.
Soda     soda.
Ammoniac     ammoniac.
Oxyd of
zinc   zinc.
manganese   manganese.
iron   iron.
lead   lead.
cobalt   cobalt.
copper   copper.
arsenic   arsenic.
mercury   mercury.
antimony   antimony.
silver   silver.
gold   gold.
platina   platina.
Argill     argill.

[Note A: These combinations were unknown to the ancient chemists. The order of affinity of the salifiable bases with this acid was determined by Mr Bergman and by Mr de Breney of the Dijon Academy. — A.]

Sect. XXVIII.Observations upon Citric Acid, and its Combinations.

The citric acid is procured by expression from lemons, and is found in the juices of many other fruits mixed with malic acid. To obtain it pure and concentrated, it is first allowed to depurate from the mucous part of the fruit by long rest in a cool cellar, and is afterwards concentrated by exposing it to the temperature of 4 or 5 degrees below Zero, from 21° to 23° of Fahrenheit, the water is frozen, and the acid remains liquid, reduced to about an eighth part of its original bulk. A lower degree of cold would occasion the acid to be engaged amongst the ice, and render it difficultly separable. This process was pointed out by Mr Georgius.

It is more easily obtained by saturating the lemon-juice with lime, so as to form a citrat of lime, which is insoluble in water; wash this salt, and pour on a proper quantity of sulphuric acid; this forms a sulphat of lime, which precipitates and leaves the citric acid free in the liquor.

Table of the Combinations of Pyro-lignous Acid with the Salifiable Bases, in the Order of Affinity(A).

Bases. Neutral Salts.
Lime   Pyro-mucite of lime.
Barytes     barytes.
Potash     potash.
Soda     soda.
Magnesia     magnesia.
Ammoniac     ammoniac.
Oxyd of
zinc   zinc.
manganese   manganese.
iron   iron.
lead   lead.
tin   tin.
cobalt   cobalt.
copper   copper.
nickel   nickel.
arsenic   arsenic.
bismuth   bismuth.
mercury   mercury.
antimony   antimony.
silver   silver.
gold   gold.
platina   platina.
Argill     argill.

[Note A: The above affinities were determined by Messrs de Morveau and EloI Boursier de Clervaux. These combinations were entirely unknown till lately. — A.]

Sect. XXIX.Observations upon Pyro-lignous Acid, and its Combinations.

The ancient chemists observed that most of the woods, especially the more heavy and compact ones, gave out a particular acid spirit, by distillation, in a naked fire; but, before Mr Goetling, who gives an account of his experiments upon this subject in Crell's Chemical Journal for 1779, no one had ever made any inquiry into its nature and properties. This acid appears to be the same, whatever be the wood it is procured from. When first distilled, it is of a brown colour, and considerably impregnated with charcoal and oil; it is purified from these by a second distillation. The pyro-lignous radical is chiefly composed of hydrogen and charcoal.

Sect. XXX.Observations upon Pyro-tartarous Acid, and its Combinations with the Salifiable Bases46.

The name of Pyro-tartarous acid is given to a dilute empyreumatic acid obtained from purified acidulous tartarite of potash by distillation in a naked fire. To obtain it, let a retort be half filled with powdered tartar, adapt a tubulated recipient, having a bent tube communicating with a bell-glass in a pneumato-chemical apparatus; by gradually raising the fire under the retort, we obtain the pyro-tartarous acid mixed with oil, which is separated by means of a funnel. A vast quantity of carbonic acid gas is disengaged during the distillation. The acid obtained by the above process is much contaminated with oil, which ought to be separated from it. Some authors advise to do this by a second distillation; but the Dijon academicians inform us, that this is attended with great danger from explosions which take place during the process.

46 The order of affinity of the salifiable bases with this acid is hitherto unknown. Mr Lavoisier, from its similarity to pyro-lignous acid, supposes the order to be the same in both; but, as this is not ascertained by experiment, the table is omitted. All these combinations, called Pyro-tartarites, were unknown till lately — E.

Table of the Combinations of Pyro-mucous Acid, with the Salifiable Bases, in the Order of Affinity(A).

Bases. Neutral Salts.
Potash   Pyro-mucite of potash.
Soda     soda.
Barytes     barytes.
Lime     lime.
Magnesia     magnesia.
Ammoniac     ammoniac.
Argill     argill.
Oxyd of
zinc   zinc.
manganese   manganese.
iron   iron.
lead   lead.
tin   tin.
cobalt   cobalt.
copper   copper.
nickel   nickel.
arsenic   arsenic.
bismuth   bismuth.
antimony   antimony.

[Note A: All these combinations were unknown to the ancient chemists. — A.]

Sect. XXXI.Observations upon Pyro-mucous Acid, and its Combinations.

This acid is obtained by distillation in a naked fire from sugar, and all the saccharine bodies; and, as these substances swell greatly in the fire, it is necessary to leave seven-eighths of the retort empty. It is of a yellow colour, verging to red, and leaves a mark upon the skin, which will not remove but alongst with the epidermis. It may be procured less coloured, by means of a second distillation, and is concentrated by freezing, as is directed for the citric acid. It is chiefly composed of water and oil slightly oxygenated, and is convertible into oxalic and malic acids by farther oxygenation with the nitric acid.

It has been pretended that a large quantity of gas is disengaged during the distillation of this acid, which is not the case if it be conducted slowly, by means of moderate heat.

Table of the Combinations of the Oxalic Acid, with the Salifiable Bases, in the Order of Affinity(A).

Bases. Neutral Salts.
Lime   Oxalat of lime.
Barytes     barytes.
Magnesia     magnesia.
Potash     potash.
Soda     soda.
Ammoniac     ammoniac.
Argill     argill.
Oxyd of
zinc   zinc.
iron   iron.
manganese   manganese.
cobalt   cobalt.
nickel   nickel.
lead   lead.
copper   copper.
bismuth   bismuth.
antimony   antimony.
arsenic   arsenic.
mercury   mercury.
silver   silver.
gold   gold.
platina   platina.

[Note A: All unknown to the ancient chemists. — A.]

Sect. XXXII.Observations upon Oxalic Acid, and its Combinations.

The oxalic acid is mostly prepared in Switzerland and Germany from the expressed juice of sorrel, from which it cristallizes by being left long at rest; in this state it is partly saturated with potash, forming a true acidulous oxalat of potash, or salt with excess of acid. To obtain it pure, it must be formed artificially by oxygenating sugar, which seems to be the true oxalic radical. Upon one part of sugar pour six or eight parts of nitric acid, and apply a gentle heat; a considerable effervescence takes place, and a great quantity of nitrous gas is disengaged; the nitric acid is decomposed, and its oxygen unites to the sugar: By allowing the liquor to stand at rest, cristals of pure oxalic acid are formed, which must be dried upon blotting paper, to separate any remaining portions of nitric acid; and, to ensure the purity of the acid, dissolve the cristals in distilled water, and cristallize them afresh.

Bases. Neutral salts. Names of the resulting neutral salts according to the old nomenclature.
Barytes Acetite of barytes Unknown to the ancients. Discovered by Mr de Morveau, who calls it barotic acéte.
Potash —— potash Secret terra foliata tartari of Muller. Arcanum tartari of Basil Valentin and Paracelsus. Purgative magistery of tartar of Schroëder. Essential salt of wine of Zwelfer. Regenerated tartar of Tachenius. Diuretic salt of Sylvius and Wilson.
Soda —— soda Foliated earth with base of mineral alkali. Mineral or crystallisable foliated earth. Mineral acetous salt.
Lime —— lime Salt of chalk, coral, or crabs eyes; mentioned by Hartman.
Magnesia —— magnesia First mentioned by Mr Wenzel.
Ammoniac —— ammoniac Spiritus Mindereri. Ammoniacal acetous salt.
Oxyd of zinc —— zinc Known to Glauber, Schwedemberg, Respour, Pott, de Lassone, and Wenzel, but not named.
—— manganese —— manganese Unknown to the ancients.
—— iron —— iron Martial vinegar. Described by Monnet, Wenzel, and the Duke d'Ayen.
—— lead —— lead Sugar, vinegar, and salt of lead or Saturn.
—— tin —— tin Known to Lemery, Margraff, Monnet, Weslendorf, and Wenzel, but not named.
—— cobalt —— cobalt Sympathetic ink of Mr Cadet.
—— copper —— copper Verdigris, crystals of verditer, verditer, distilled verdigris, crystals of Venus or of copper.
—— nickel —— nickel Unknown to the ancients.
—— arsenic —— arsenic Arsenico-acetous fuming liquor, liquid phosphorus of Mr Cadet.
—— bismuth —— bismuth Sugar of bismuth of Mr Geoffroi. Known to Gellert, Pott, Weslendorf, Bergman, and de Morveau.
—— mercury —— mercury Mercurial foliated earth, Keyser's famous antivenereal remedy. Mentioned by Gebaver in 1748; known to Helot, Margraff, Baumé, Bergman, and de Morveau.
—— antimony —— antimony Unknown.
—— silver —— silver Described by Margraff, Monnet, and Wenzel; unknown to the ancients.
—— gold —— gold Little known, mentioned by Schroëder and Juncker.
—— platina —— platina Unknown.
Argill —— argill According to Mr Wenzel, vinegar dissolves only a very small proportion of argill.

From the liquor remaining after the first cristallization of the oxalic acid we may obtain malic acid by refrigeration: This acid is more oxygenated than the oxalic; and, by a further oxygenation, the sugar is convertible into acetous acid, or vinegar.

The oxalic acid, combined with a small quantity of soda or potash, has the property, like the tartarous acid, of entering into a number of combinations without suffering decomposition: These combinations form triple salts, or neutral salts with double bases, which ought to have proper names. The salt of sorrel, which is potash having oxalic acid combined in excess, is named acidulous oxalat of potash in our new nomenclature.

The acid procured from sorrel has been known to chemists for more than a century, being mentioned by Mr Duclos in the Memoirs of the Academy for 1688, and was pretty accurately described by Boerhaave; but Mr Scheele first showed that it contained potash, and demonstrated its identity with the acid formed by the oxygenation of sugar.

Sect. XXXIII.Observations upon Acetous Acid, and its Combinations.

This acid is composed of charcoal and hydrogen united together, and brought to the state of an acid by the addition of oxygen; it is consequently formed by the same elements with the tartarous oxalic, citric, malic acids, and others, but the elements exist in different proportions in each of these; and it would appear that the acetous acid is in a higher state of oxygenation than these other acids. I have some reason to believe that the acetous radical contains a small portion of azote; and, as this element is not contained in the radicals of any vegetable acid except the tartarous, this circumstance is one of the causes of difference. The acetous acid, or vinegar, is produced by exposing wine to a gentle heat, with the addition of some ferment: This is usually the ley, or mother, which has separated from other vinegar during fermentation, or some similar matter. The spiritous part of the wine, which consists of charcoal and hydrogen, is oxygenated, and converted into vinegar: This operation can only take place with free access of air, and is always attended by a diminution of the air employed in consequence of the absorption of oxygen; wherefore, it ought always to be carried on in vessels only half filled with the vinous liquor submitted to the acetous fermentation. The acid formed during this process is very volatile, is mixed with a large proportion of water, and with many foreign substances; and, to obtain it pure, it is distilled in stone or glass vessels by a gentle fire. The acid which passes over in distillation is somewhat changed by the process, and is not exactly of the same nature with what remains in the alembic, but seems less oxygenated: This circumstance has not been formerly observed by chemists.

Distillation is not sufficient for depriving this acid of all its unnecessary water; and, for this purpose, the best way is by exposing it to a degree of cold from 4° to 6° below the freezing point, from 19° to 23° of Fahrenheit; by this means the aqueous part becomes frozen, and leaves the acid in a liquid state, and considerably concentrated. In the usual temperature of the air, this acid can only exist in the gasseous form, and can only be retained by combination with a large proportion of water. There are other chemical processes for obtaining the acetous acid, which consist in oxygenating the tartarous, oxalic, or malic acids, by means of nitric acid; but there is reason to believe the proportions of the elements of the radical are changed during this process. Mr Hassenfratz is at present engaged in repeating the experiments by which these conversions are said to be produced.

The combinations of acetous acid with the various salifiable bases are very readily formed; but most of the resulting neutral salts are not cristallizable, whereas those produced by the tartarous and oxalic acids are, in general, hardly soluble. Tartarite and oxalat of lime are not soluble in any sensible degree: The malats are a medium between the oxalats and acetites, with respect to solubility, and the malic acid is in the middle degree of saturation between the oxalic and acetous acids. With this, as with all the acids, the metals require to be oxydated previous to solution.

The ancient chemists knew hardly any of the salts formed by the combinations of acetous acid with the salifiable bases, except the acetites of potash, soda, ammoniac, copper, and lead. Mr Cadet discovered the acetite of arsenic47; Mr Wenzel, the Dijon academicians Mr de Lassone, and Mr Proust, made us acquainted with the properties of the other acetites. From the property which acetite of potash possesses, of giving out ammoniac in distillation, there is some reason to suppose, that, besides charcoal and hydrogen, the acetous radical contains a small proportion of azote, though it is not impossible but the above production of ammoniac may be occasioned by the decomposition of the potash.

47 Savans Etrangers, Vol. III.

Table of the Combinations of Acetic Acid with the Salifiable Bases, in the order of affinity.

Bases. Neutral Salts.
Barytes   Acetat of barytes.
Potash     potash.
Soda     soda.
Lime     lime.
Magnesia     magnesia.
Ammoniac     ammoniac.
Oxyd of zinc   zinc.
manganese   manganese.
iron   iron.
lead   lead.
tin   tin.
cobalt   cobalt.
copper   copper.
nickel   nickel.
arsenic   arsenic.
bismuth   bismuth.
mercury   mercury.
antimony   antimony.
silver   silver.
gold   gold.
platina   platina.
Argill     argill.

Note.— All these salts were unknown to the ancients; and even those chemists who are most versant in modern discoveries, are yet at a lose whether the greater part of the salts produced by the oxygenated acetic radical belong properly to the class of acetites, or to that of acetats. — A.

Sect. XXXIV.Observations upon Acetic Acid, and its Combinations.

We have given to radical vinegar the name of acetic acid, from supposing that it consists of the same radical with that of the acetous acid, but more highly saturated with oxygen. According to this idea, acetic acid is the highest degree of oxygenation of which the hydro-carbonous radical is susceptible; but, although this circumstance be extremely probable, it requires to be confirmed by farther, and more decisive experiments, before it be adopted as an absolute chemical truth. We procure this acid as follows: Upon three parts acetite of potash or of copper, pour one part of concentrated sulphuric acid, and, by distillation, a very highly concentrated vinegar is obtained, which we call acetic acid, formerly named radical vinegar. It is not hitherto rigorously proved that this acid is more highly oxygenated than the acetous acid, nor that the difference between them may not consist in a different proportion between the elements of the radical or base.

Table of the Combinations of Succinic Acid with the Salifiable Bases, in the order of Affinity.

Bases. Neutral Salts.
Barytes   Succinat of barytes.
Lime     lime.
Potash     potash.
Soda     soda.
Ammoniac     ammoniac.
Magnesia     magnesia.
Argill     argill.
Oxyd of zinc   zinc.
iron   iron.
manganese   manganese.
cobalt   cobalt.
nickel   nickel.
lead   lead.
tin   tin.
copper   copper.
bismuth   bismuth.
antimony   antimony.
arsenic   arsenic.
mercury   mercury.
silver   silver.
gold   gold.
platina   platina.

Note.— All the succinats were unknown to the ancient chemists. — A.

Sect. XXXV.Observations upon Succinic Acid, and its Combinations.

The succinic acid is drawn from amber by sublimation in a gentle heat, and rises in a concrete form into the neck of the subliming vessel. The operation must not be pushed too far, or by too strong a fire, otherwise the oil of the amber rises alongst with the acid. The salt is dried upon blotting paper, and purified by repeated solution and crystallization.

This acid is soluble in twenty-four times its weight of cold water, and in a much smaller quantity of hot water. It possesses the qualities of an acid in a very small degree, and only affects the blue vegetable colours very slightly. The affinities of this acid, with the salifiable bases, are taken from Mr de Morveau, who is the first chemist that has endeavoured to ascertain them.

Sect. XXXVI. —Observations upon Benzoic Acid, and its Combinations with Salifiable Bases48.

This acid was known to the ancient chemists under the name of Flowers of Benjamin, or of Benzoin, and was procured, by sublimation, from the gum or resin called Benzoin: The means of procuring it, via humida, was discovered by Mr Geoffroy, and perfected by Mr Scheele. Upon benzoin, reduced to powder, pour strong lime-water, having rather an excess of lime; keep the mixture continually stirring, and, after half an hour's digestion, pour off the liquor, and use fresh portions of lime-water in the same manner, so long as there is any appearance of neutralization. Join all the decanted liquors, and evaporate, as far as possible, without occasioning cristallization, and, when the liquor is cold, drop in muriatic acid till no more precipitate is formed. By the former part of the process a benzoat of lime is formed, and, by the latter, the muriatic acid combines with the lime, forming muriat of lime, which remains dissolved, while the benzoic acid, being insoluble, precipitates in a concrete state.

48 These combinations are called Benzoats of Lime, Potash, Zinc, &c.; but, as the order of affinity is unknown, the alphabetical table is omitted, as unnecessary. — E.

Sect. XXXVII. —Observations upon Camphoric Acid, and its Combinations with Salifiable Bases49.

Camphor is a concrete essential oil, obtained, by sublimation, from a species of laurus which grows in China and Japan. By distilling nitric acid eight times from camphor, Mr Kosegarten converted it into an acid analogous to the oxalic; but, as it differs from that acid in some circumstances, we have thought necessary to give it a particular name, till its nature be more completely ascertained by farther experiment.

As camphor is a carbono-hydrous or hydro-carbonous radical, it is easily conceived, that, by oxygenation, it should form oxalic, malic, and several other vegetable acids: This conjecture is rendered not improbable by the experiments of Mr Kosegarten; and the principal phenomena exhibited in the combinations of camphoric acid with the salifiable bases, being very similar to those of the oxalic and malic acids, lead me to believe that it consists of a mixture of these two acids.

49 These combinations, which were all unknown to the ancients, are called Camphorats. The table is omitted, as being only in alphabetical order. — E.

Sect. XXXVIII. —Observations upon Gallic Acid, and its Combinations with Salifiable Bases50.

The Gallic acid, formerly called Principle of Astringency, is obtained from gall nuts, either by infusion or decoction with water, or by distillation with a very gentle heat. This acid has only been attended to within these few years. The Committee of the Dijon Academy have followed it through all its combinations, and give the best account of it hitherto produced. Its acid properties are very weak; it reddens the tincture of turnsol, decomposes sulphurets, and unites to all the metals when they have been previously dissolved in some other acid. Iron, by this combination, is precipitated of a very deep blue or violet colour. The radical of this acid, if it deserves the name of one, is hitherto entirely unknown; it is contained in oak willow, marsh iris, the strawberry, nymphea, Peruvian bark, the flowers and bark of pomgranate, and in many other woods and barks.

50 These combinations, which are called Gallats, were all unknown to the ancients; and the order of their affinity is not hitherto established. — A.

Sect. XXXIX. —Observations upon Lactic Acid, and its Combinations with Salifiable Bases51.

The only accurate knowledge we have of this acid is from the works of Mr Scheele. It is contained in whey, united to a small quantity of earth, and is obtained as follows: Reduce whey to one eighth part of its bulk by evaporation, and filtrate, to separate all its cheesy matter; then add as much lime as is necessary to combine with the acid; the lime is afterwards disengaged by the addition of oxalic acid, which combines with it into an insoluble neutral salt. When the oxalat of lime has been separated by decantation, evaporate the remaining liquor to the consistence of honey; the lactic acid is dissolved by alkohol, which does not unite with the sugar of milk and other foreign matters; these are separated by filtration from the alkohol and acid; and the alkohol being evaporated, or distilled off, leaves the lactic acid behind.

This acid unites with all the salifiable bases forming salts which do not cristallize; and it seems considerably to resemble the acetous acid.

51 These combinations are called Lactats; they were all unknown to the ancient chemists, and their affinities have not yet been ascertained. — A.

Table of the Combinations of Saccholactic Acid with the Salifiable Bases, in the Order of Affinity.

Bases. Neutral Salts.
Lime   Saccholat of lime.
Barytes     barytes.
Magnesia     magnesia.
Potash     potash.
Soda     soda.
Ammoniac     ammoniac.
Argill     argill.
Oxyd of zinc   zinc.
manganese   manganese.
iron   iron.
lead   lead.
tin   tin.
cobalt   cobalt.
copper   copper.
nickel   nickel.
arsenic   arsenic.
bismuth   bismuth.
mercury   mercury.
antimony   antimony.
silver   silver.

Note.— All these were unknown to the ancient chemists. — A.

Sect. XL. —Observations upon Saccholactic Acid, and its Combinations.

A species of sugar may be extracted, by evaporation, from whey, which has long been known in pharmacy, and which has a considerable resemblance to that procured from sugar canes. This saccharine matter, like ordinary sugar, may be oxygenated by means of nitric acid: For this purpose, several portions of nitric acid are distilled from it; the remaining liquid is evaporated, and set to cristallize, by which means cristals of oxalic acid are procured; at the same time a very fine white powder precipitates, which is the saccholactic acid discovered by Scheele. It is susceptible of combining with the alkalies, ammoniac, the earths, and even with the metals: Its action upon the latter is hitherto but little known, except that, with them, it forms difficultly soluble salts. The order of affinity in the table is taken from Bergman.

Table of the Combinations of Formic Acid, with the Salifiable Bases, in the Order of Affinity.

Bases. Neutral Salts.
Barytes   Formiat of barytes.
Potash     potash.
Soda     soda.
Lime     lime.
Magnesia     magnesia.
Ammoniac     ammoniac.
Oxyd of
zinc   zinc.
manganese   manganese.
iron   iron.
lead   lead.
tin   tin.
cobalt   cobalt.
copper   copper.
nickel   nickel.
bismuth   bismuth.
silver   silver.
Argill     argill.

Note.— All unknown to the ancient chemists. — A.

Sect. XLI. —Observations upon Formic Acid, and its Combinations.

This acid was first obtained by distillation from ants, in the last century, by Samuel Fisher. The subject was treated of by Margraff in 1749, and by Messrs Ardwisson and Ochrn of Leipsic in 1777. The formic acid is drawn from a large species of red ants, formica rufa, Lin. which form large ant hills in woody places. It is procured, either by distilling the ants with a gentle heat in a glass retort or an alembic; or, after having washed the ants in cold water, and dried them upon a cloth, by pouring on boiling water, which dissolves the acid; or the acid may be procured by gentle expression from the insects, in which case it is stronger than in any of the former ways. To obtain it pure, we must rectify, by means of distillation, which separates it from the uncombined oily and charry matter; and it may be concentrated by freezing, in the manner recommended for treating the acetous acid.

Sect. XLII. —Observations upon Bombic Acid, and its Combinations with Acidifiable Bases52.

The juices of the silk worm seem to assume an acid quality when that insect changes from a larva to a chrysalis. At the moment of its escape from the latter to the butterfly form, it emits a reddish liquor which reddens blue paper, and which was first attentively observed by Mr Chaussier of the Dijon academy, who obtains the acid by infusing silk worm chrysalids in alkohol, which dissolves their acid without being charged with any of the gummy parts of the insect; and, by evaporating the alkohol, the acid remains tollerably pure. The properties and affinities of this acid are not hitherto ascertained with any precision; and we have reason to believe that analogous acids may be procured from other insects. The radical of this acid is probably, like that of the other acids from the animal kingdom, composed of charcoal, hydrogen, and azote, with the addition, perhaps, of phosphorus.

52 These combinations named Bombats were unknown to the ancient chemists; and the affinities of the salifiable bases with the bombic acid are hitherto undetermined. — A.

Table of the Combinations of Sebacic Acid, with the Salifiable Bases, in the Order of Affinity.

Bases. Neutral Salts.
Barytes   Sebat of barytes.
Potash     potash.
Soda     soda.
Lime     lime.
Magnesia     magnesia.
Ammoniac     ammoniac.
Argill     argill.
Oxyd of
zinc   zinc.
manganese   manganese.
iron   iron.
lead   lead.
tin   tin.
cobalt   cobalt.
copper   copper.
nickel   nickel.
arsenic   arsenic.
bismuth   bismuth.
mercury   mercury.
antimony   antimony.
silver   silver.

Note.— All these were unknown to the ancient chemists. — A.

Sect. XLIII. —Observations upon Sebacid Acid, and its Combinations.

To obtain the sebacic acid, let some suet be melted in a skillet over the fire, alongst with some quick-lime in fine powder, and constantly stirred, raising the fire towards the end of the operation, and taking care to avoid the vapours, which are very offensive. By this process the sebacic acid unites with the lime into a sebat of lime, which is difficultly soluble in water; it is, however, separated from the fatty matters with which it is mixed by solution in a large quantity of boiling water. From this the neutral salt is separated by evaporation; and, to render it pure, is calcined, redissolved, and again cristallized. After this we pour on a proper quantity of sulphuric acid, and the sebacic acid passes over by distillation.

Sect. XLIV.Observations upon the Lithic Acid, and its Combinations with the Salifiable Bases53.

From the later experiments of Bergman and Scheele, the urinary calculus appears to be a species of salt with an earthy basis; it is slightly acidulous, and requires a large quantity of water for solution, three grains being scarcely soluble in a thousand grains of boiling water, and the greater part again cristallizes when cold. To this concrete acid, which Mr de Morveau calls Lithiasic Acid, we give the name of Lithic Acid, the nature and properties of which are hitherto very little known. There is some appearance that it is an acidulous neutral salt, or acid combined in excess with a salifiable base; and I have reason to believe that it really is an acidulous phosphat of lime; if so, it must be excluded from the class of peculiar acids.

53 All the combinations of this acid, should it finally turn out to be one, were unknown to the ancient chemists, and its affinities with the salifiable bases have not been hitherto determined. — A.

Table of the Combinations of the Prussic Acid with the Salifiable Bases, in the order of affinity.

Bases. Neutral Salts.
Potash   Prussiat of potash.
Soda     soda.
Ammoniac     ammoniac.
Lime     lime.
Barytes     barytes.
Magnesia     magnesia.
Oxyd of zinc   zinc.
iron   iron.
manganese   manganese.
cobalt   cobalt.
nickel   nickel.
lead   lead.
tin   tin.
copper   copper.
bismuth   bismuth.
antimony   antimony.
arsenic   arsenic.
silver   silver.
mercury   mercury.
gold   gold.
platina   platina.

Note.—-All these were unknown to former chemists. — A.

Observations upon the Prussic Acid, and its Combinations.

As the experiments which have been made hitherto upon this acid seem still to leave a considerable degree of uncertainty with regard to its nature, I shall not enlarge upon its properties, and the means of procuring it pure and dissengaged from combination. It combines with iron, to which it communicates a blue colour, and is equally susceptible of entering into combination with most of the other metals, which are precipitated from it by the alkalies, ammoniac, and lime, in consequence of greater affinity. The Prussic radical, from the experiments of Scheele, and especially from those of Mr Berthollet, seems composed of charcoal and azote; hence it is an acid with a double base. The phosphorus which has been found combined with it appears, from the experiments of Mr Hassenfratz, to be only accidental.

Although this acid combines with alkalies, earths, and metals, in the same way with other acids, it possesses only some of the properties we have been in use to attribute to acids, and it may consequently be improperly ranked here in the class of acids; but, as I have already observed, it is difficult to form a decided opinion upon the nature of this substance until the subject has been farther elucidated by a greater number of experiments.

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