The substitution of a large balloon, having a capacity of about 2 litres, in place of the small vessel of Flandin and Danger's apparatus, is to be recommended as doing away with the necessity of evaporation; an operation which invariably causes a loss of substance. The apparatus, modified in this manner, is the most delicate in use for the detection of mercury. DETECTION OF PHOSPHORUS. ORFILA'S METHOD. The solid substances found in the alimentary canal are mechanically separated from the fluids present by means of a linen cloth. They are then examined by aid of a magnifying glass, and any fragments of phosphorus found separated and preserved under water. If none are discovered, the presence of phosphorescent vapors may possibly be detected by examining the materials in the dark. In any case, a portion of the suspected materials should be treated with nitrate of silver: in presence of phosphorus the materials acquire, first, a reddish-brown, then, a black color. The remaining portion is spread upon a shovel and heated: a white flame, burning at various points of the mass, and originating from the combustion of phosphorus, is observed, if this body be contained in the substances under examination. This method is evidently far from perfect. MITSCHERLICH'S METHOD. Mistcherlich's method is based upon the luminosity of the vapors of phosphorus. The suspected materials are moistened with dilute sulphuric acid, and heated, in a flask communicating with a glass worm which passes through a glass cooler into a receiver. If the apparatus is placed in the dark, and the materials contain phosphorus, luminous vapors will be observed in the flask and receiver. When the quantity of the poison present is considerable, the phosphorous acid formed can be collected and its properties tested. DUSART'S METHOD, AS MODIFIED BY BLONDLOT. [Illustration: Fig. 10.]