By the above process, one part of phosphorus may be detected in 100,000 parts of substance. Another method for the detection of this poison in very minute quantities is that proposed by Dussart (_Compt. Rend._, xliii. 1126), and modified by Blondlot (_Compt. Rend._, lii. 1197). The test is based on the fact that when phosphorus is exposed to the action of _nascent hydrogen_ in a Marsh‘s apparatus, it burns with an emerald-green flame. In order to avoid the yellow colouring of the flame produced by the sodium in glass, Blondlot recommends the use of a platinum jet. As the green colour is more or less interfered with by the presence of organic matters, he passes the gas through a solution of nitrate of silver; the resulting precipitate is then placed in another hydrogen apparatus, as just mentioned, and the colour of the flame of the issuing gas noted. Phosphorus may become decomposed in the body; and as phosphoric acid is taken in most articles of food, the only satisfactory evidence of phosphorus having been taken is to produce it in its free state, or at least to exhibit its luminosity. The detection of the colouring matter of lucifer matches in the stomach or vomited matters will point to the probable nature of the poison, and whence it was derived. _Scherer‘s Test_ is based on the reducing action of phosphorus on nitrate of silver, which it blackens. The suspected material should be placed in a flask or in a Dowzard‘s apparatus for Gutzeit‘s test for arsenic, lead acetate is added to the material to fix the H₂S, and some lead acetate solution placed in each cell. A little ether is added to the mixture, and the flask or top of the apparatus capped with paper moistened with nitrate of silver, and set aside for some hours in a dark place. If phosphorus be present the paper will be blackened from deposition of metallic silver. _Fatal Period._--From half an hour to twenty days or more. _Fatal Dose._--One grain and a half. The smallest fatal dose recorded for an adult is one-eighth of a grain. An infant five weeks old died from sucking a single match head, which probably contained one-fiftieth of a grain of phosphorus. Recovery has taken place after four and six grains have been taken. _Treatment._--The stomach pump or syphon tube should be used as soon as possible, and the stomach well washed out with warm water containing a drachm of old oil of turpentine to the pint. If the turpentine be not readily obtained, “sanitas” should be used with the water, or a 1 per cent. solution of permanganate of potash. After washing the stomach, the old oil of turpentine, or the French oil of turpentine, or “sanitas” may be administered in half to one drachm doses in mucilage and water every fifteen minutes for several doses, and afterwards three or four times daily. The 1 per cent. solution of potassium permanganate may be administered in copious drinks.