12-1/2 atoms of carbon 93.75 or 31.5128 2-1/2 " azote 43.75 " 14.7060 16 " oxygen 160.00 " 53.7812 ------- -------- 297.5 100. 100 parts of the acid neutralize a quantity of base equivalent to 3.26 of oxygen, which is to the oxygen of the acid, as 1:16; the equivalent number of the acid derived from the analysis of the [p212] barytic salt was 306.3; by adding only 1/4 per cent. to the quantity of baryta obtained in the experiment, 297.5, or the number expressed by the above formula, would be obtained. When a salt of potash or baryta was decomposed by oxide of copper and heat, the quantity of carbonic acid produced was a little short of five times the quantity of nitrogen; but, upon adding that retained by the alkali or earth, the proportion became exactly the same as in the former cases. _Welter’s bitter principle_ was prepared by acting on silk with ten or twelve times its weight of nitric acid. The liquid, slightly coloured at first, acquired a deep yellow upon adding water. It was neutralized by carbonate of potash whilst hot, and left to cool, and the salt of potash thus obtained, decomposed by muriatic, nitric, or sulphuric acid. This acid, crystallized like that from indigo, formed the same salts, and was composed in the same manner. Silk furnishes much less of the substance than indigo. Dr. Liebeg has called this substance _carbazotic acid_. The most important salts formed by it have the following properties:— _Carbazotate of Potash_—crystallizes in long yellow quadrilateral needles, semi-transparent and very brilliant; it dissolves in 260 parts of water at 59° F., and in much less, boiling water: a saturated boiling solution becomes a yellow mass of needles, from which scarcely any fluid will run. Strong acids decompose it; yet when an alcoholic solution of carbazotic acid is added to a solution of nitre, crystallized carbazotate of potash, after some time, precipitates.—Alcohol does not dissolve it. When a little is gradually heated in a glass tube, it first fuses, and then suddenly explodes, breaking the tube to atoms; traces of charcoal are observed on the fragments. This salt precipitates a solution of the protonitrate of mercury, but not salts, containing the peroxide, or those of copper, lead, cobalt, iron, lime, baryta, strontia, or magnesia. The slight solubility of this salt supplies an easy method of testing and separating potash in a fluid. Even the potash in tincture of litmus may be discovered by it; for, on adding a few drops of carbazotic acid, dissolved in alcohol, to infusion of litmus, crystals of the salt gradually separated. The saturated solution of the salt at 50° F., is not troubled by muriate of platina. The salt contains no water of crystallization. It was analyzed by converting a portion of it into chloride of potassium by muriatic acid: its composition is,—