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.

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 cla.s.s of acet.i.tes, or to that of acetats.--A.

SECT. x.x.xIV.--_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 circ.u.mstance 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 acet.i.te 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.

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

antimony antimony.

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

mercury mercury.

silver silver.

gold gold.

platina platina.

_Note._--All the succinats were unknown to the ancient chemists.--A.

SECT. x.x.xV.--_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 quant.i.ty 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. x.x.xVI.--_Observations upon Benzoic Acid, and its Combinations with Salifiable Bases[48]._

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.

SECT. x.x.xVII.--_Observations upon Camphoric Acid, and its Combinations with Salifiable Bases[49]._

Camphor is a concrete essential oil, obtained, by sublimation, from a species of laurus which grows in China and j.a.pan. By distilling nitric acid eight times from camphor, Mr Kosegarten converted it into an acid a.n.a.logous to the oxalic; but, as it differs from that acid in some circ.u.mstances, 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 princ.i.p.al 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.

SECT. x.x.xVIII.--_Observations upon Gallic Acid, and its Combinations with Salifiable Bases[50]._

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. .h.i.therto 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.

SECT. x.x.xIX.--_Observations upon Lactic Acid, and its Combinations with Salifiable Bases[51]._

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 quant.i.ty 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.

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.