CHEMICAL TOXICOLOGY 291 



vacuum to a small bulk. Water is added (20 to 50 c.c.) 

 to the residue, and the mixture thoroughly shaken and 

 filtered, the clear aqueous solution being collected in a 

 separating funnel. The insoluble part is generally chiefly 

 composed of fat, and ordinarily need not be further ex- 

 amined, although it may contain such drastic oils as 

 croton. 



The result of the processes is the obtaining of a watery 

 extract of acid reaction, in which is concentrated the 

 organic poison, and which has been moderately freed from 

 organic products natural to flesh, tissues, and ingesta. It 

 is always coloured, varying from pale yellow to dark 

 brown. 



PreliminaFy Observations on the Water Extract.— 

 A tendency to foam and generally to simulate soap solution 

 points to saponins. 



Ferric chloride gives a red colour with meconic acid 

 (from opium) in the acid solution. In a neutral solution 

 ferric chloride gives violet colours with phenol, morphine, 

 and salicylic acid, and a blue-black or black with tannins 

 and gallic acid. 



Extraction of the Constituents of the Water Extract. 

 — The separation of the substances likely to be present in 

 the water extract is effected through extraction of the 

 water solution by means of organic solvents, which do not 

 mix with or are only partially soluble in water, such as 

 petroleum ether, ether, benzene, chloroform, ethyl acetate, 

 and amyl alcohol. The nature of the substance extracted 

 depends on the reaction of the water solution. If the 

 solution is acid, solvents extract free acids, glucosides, and 

 bitter principles; if it is alkaline, solvents extract alka- 

 loids ; if neutral, glucosides. Morphine is not extracted in 

 the presence of strong alkali (sodium hydroxide), since 

 being a phenol it forms salts of the alkali metals. It is, 

 however, extracted from ammonia or sodium bicarbonate 

 solution, since these are not strong enough alkalis to form 

 salts with morphine. In practice it is sufficient to make 

 alkaline with ammonia or bicarbonate as a usual procedure. 



