284 EXAMINATION FOR PHOSPHORUS. 



emerald-green coloration of the flame will be percep- 

 tible. 



b. The SOLUTION filtered from the silver precipitate, 

 is freed from excess of silver by hydrochloric acid, 

 filtered through a well purified filter, strongly concen- 

 trated in a porcelain capsule, and finally tested for 

 phosphoric acid by means of molybdate of ammonia or 

 magnesia mixture. 



In this manner we have most plainly detected the 

 phosphorus of a common match mixed with a large 

 quantity of putrefied blood, and in presence of those 

 substances which prevent luminosity in the method of 

 Mitscherlich. 



V. When enough phosphorus is present to weigh, 

 its estimation is practicable by adopting Scherer's 

 modification of the process of Mitscherlich. The mass, 

 acidified with sulphuric acid, is distilled in an atmos- 

 phere of carbonic acid gas. For this purpose it is best 

 to fit into the cork of the flask in which the mixture 

 is distilled, a second tube through which pure carbonic 

 acid may be transmitted into the distilling apparatus, 

 until it is completely filled, when the stream of gas 

 may be cut off and the process continued as usual. 

 The receiver may consist of a flask with a doubly 

 perforated cork, the opening of which passes over the 

 end of the condensing tube, the other carrying a bent 

 glass tube which is connected with a U tube containing 

 solution of nitrate of silver. 



When the distillation is finished, globules of phos- 

 phorus are found in the receiver, which, after again 

 establishing a gentle stream of carbonic acid, are united 

 by gently heating and then are washed and weighed 

 as described (III. a.). The solution poured off from 

 the globules is luminous in the dark, when shaken, 

 though not to the same degree as in Mitscherlich 1 s 

 process. The phosphorus in this liquid may be deter- 

 mined, after oxidation, by nitric acid or chlorine, as 



