§ 300. =How long can Phosphorus be recognised after Death?=--One of the most important matters for consideration is the time after death in which free phosphorus, or free phosphoric acids, can be detected. Any phosphorus changed into ammon. mag. phosphate, or into any other salt, is for medico-legal purposes entirely lost, since the expert can only take cognisance of the substance either in a free state, as phosphine, or as a free acid. The question, again, may be asked in court--Does the decomposition of animal substances rich in phosphorus develop phosphine? The answer to this is, that no such reaction has been observed. A case is related[322] in which phosphorus was recognised, although the body had been buried for several weeks and then exhumed. [322] _Pharm. Zeitsch. f. Russl._, Jahrg. 2, p. 87. The expert of pharmacy of the Provincial Government Board of Breslau has also made some experiments in this direction, which are worthy of note:--Four guinea-pigs were poisoned, each by 0·023 grm. of phosphorus; they died in a few hours, and were buried in sandy-loam soil, 0·5 metre deep. Exhumation of the first took place four weeks after. The putrefying organs--heart, liver, spleen, stomach, and all the intestines--tested by Mitscherlich’s method of distillation, showed characteristic phosphorescence for nearly one hour. The second animal was exhumed after eight weeks in a highly putrescent state. Its entrails, on distillation, showed the phosphorescent appearance for thirty-five minutes. The third animal was taken from the earth after twelve weeks, but no free phosphorus could be detected, although there was evidence of the lower form of oxidation (PO₃) by Blondlot’s method. The fourth animal was exhumed after fifteen weeks, but neither free phosphorus nor PO₃ could be detected.[323] [323] _Vierteljahrsschrift für gerichtliche Medicin_, Jan. 7, 1876; see also _Zeitschr. f. anal. Chemie_, 1872. A man, as well as a cat, was poisoned by phosphorus. On analysis, twenty-nine days after death, negative results were alone obtained.--_Sonnenschein._ It will thus be evident that there is no constant rule, and that, even when decomposition is much advanced, an examination _may_ be successful. PART VI.--ALKALOIDS AND POISONOUS VEGETABLE PRINCIPLES SEPARATED FOR THE MOST PART BY ALCOHOLIC SOLVENTS. DIVISION I.--VEGETABLE ALKALOIDS. I.--General Methods of Testing and Extracting Alkaloids. § 301. =General Tests for Alkaloids.=--In order to ascertain whether an alkaloid is present or not, a method of extraction must be pursued which, while disposing of fatty matters, salts, &c., shall dissolve as little as possible of foreign substances--such a method, _e.g._, as the original process of Stas, or one of its modern modifications.