lead lead.

tin tin.

cobalt cobalt.

copper copper.

nickel nickel.

a.r.s.enic a.r.s.enic.

bis.m.u.th bis.m.u.th.

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. .h.i.therto 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.

bis.m.u.th bis.m.u.th.

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 gla.s.s 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 Bases[52]._

The juices of the silk worm seem to a.s.sume an acid quality when that insect changes from a larva to a chrysalis. At the moment of its escape from the latter to the b.u.t.terfly 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 a.n.a.logous 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.

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.

a.r.s.enic a.r.s.enic.

bis.m.u.th bis.m.u.th.

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 quant.i.ty 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 quant.i.ty of sulphuric acid, and the sebacic acid pa.s.ses over by distillation.

SECT. XLIV.--_Observations upon the Lithic Acid, and its Combinations with the Salifiable Bases[53]._

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 quant.i.ty 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 cla.s.s of peculiar acids.

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.