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. tin tin Aerated tin. copper copper Aerated copper. bismuth bismuth Aerated bismuth. antimony antimony Aerated antimony. arsenic arsenic Aerated arsenic. mercury mercury Aerated mercury. silver silver Aerated silver. gold gold Aerated gold. platina platina Aerated 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 _aerated_; 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.