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.

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._--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 pa.s.ses 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_ _Names of the Neutral Salts formed by_ _Bases._ _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.

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

antimony antimony antimony.

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

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-gla.s.ses, 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 gla.s.s 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 gla.s.s-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_ _Resulting Neutral Salts._ _Bases_ _New Nomenclature._ _Old Nomenclature._

Barytes Carbonates of barytes(A) Aerated or effervescent heavy earth.

Lime lime {Chalk, calcareous spar, { Aerated calcareous earth.

Potash potash {Effervescing or aerated fixe { vegetable alkali, mephitis of { potash.

Soda soda {Aerated or effervescing fixed mineral { alkali, mephitic soda.

Magnesia magnesia {Aerated, effervescing, mild, or { mephitic magnesia.

Ammoniac ammoniac {Aerated, effervescing, mild, or { mephitic volatile alkali.

Argill argill {Aerated or effervescing argillaceous { earth, or earth of alum.

Oxyds of zinc zinc Zinc spar, mephitic or aerated zinc.

iron iron Sparry iron-ore, mephitic or aerated iron.

manganese manganese Aerated manganese.

cobalt cobalt Aerated cobalt.

nickel nickel Aerated nickel.

lead lead Sparry lead-ore, or aerated lead.