Principles of pharmacy

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 edition. Excerpt: ...was supposed to be as follows: Hg + I = Hgl, but, as a matter of fact, it partly runs as follows: Hg + I, = HgI2, with the formation of mercuric iodide. This mercuric iodide was removed by the process of the pharmacopoeia of 1880 by washing the mixture with alcohol. Mercurous iodide, like mercuric iodide, is used as an alterative, but is a much milder preparation, as is shown by the doses. Dose.--10 milligrammes % grain). While the two iodides are mercurous and mercuric respectively, both oxides of mercury are "ic" salts, having the formula HgO, and giving an interesting example of physical difference of two bodies that are chemically identical. Their mutual identity is proved by the fact that red oxide, when finely triturated, turns yellow, while the yellow, on heating, is converted into the red. HYDRARGYRI OXIDUM FLAVUM--Yellow Mercuric Oxide (Hydrarg. Oxid. Flav.) It contains, when dried to constant weight at 150C, not less than 99.5 per cent, of HgO (216.60). Preserve it in well-closed containers, protected from light. Summarized Description. Light orange-yellow amorphous, heavy, impalpable powder; somewhat metallic taste; turns somewhat dark on exposure to light; almost insoluble in water; insoluble in alcohol; soluble in diluted hydrochloric or nitric acids; on heating, it first turns red and then dissociates into oxygen and metallic mercury. For details see U.S. P., p. 217. For tests for identity, for impurities (red mercuric oxide) and for assay see U.S.P., p. 217 and also Part V of this book. Remarks.--Yellow mercuric oxide is made by treating bichloride of mercury with the requisite amount of sodium hydroxide as shown in the following equation: HgCU + 2NaOH = HgO + H,0 + 2NaCl. As a result, mercuric oxide is...