124 DETECTION OF ARSENIC. 



red colour. The remaining portion of the solution may then 

 be treated with sulphuretted hydrogen gas, or water containing 

 that gas in solution, and the bright yellow coloured precipitate 

 is thrown down, as shewn in the former example. This pre- 

 cipitate, dried, mixed with the flux, and submitted to the re- 

 ducing experiment, yields the ring, the crystals, and other 

 characteristics of the metal, which will be readily recognized 

 by an experienced operator. As preliminary to these more 

 minute experiments, the carbonaceous mass, resulting from 

 the action of the acids may be thrown upon burning coals, 

 when the well known alliaceous odour will be exhaled if 

 arsenic be present in the mass. 



The operations necessary under two forms, in which chemists 

 may be called upon to show the presence of arsenic have now 

 been detailed ; there are two general heads yet remaining, 

 requiring attention. These are where arsenic may have been 

 mingled with liquid food, as soup, tea, milk, &c. <fcc. and 

 finally, where neither the food which had been eaten, nor the 

 matter which had been vomited, is accessible, we are compelled 

 to avail ourselves of the contents of the stomach, or even of 

 the substance of that organ itself. The proceeding in both of 

 these cases is almost precisely analogous to that last described. 

 In both of them we have the poison mixed with organic mat- 

 ter, and so far they resemble it and must be subjected to the 

 de-organizing powers of the strong mineral acids heretofore 

 alluded to. But anterior to the application of the acids there 

 are one or two minor operations, which it were well to describe. 

 In the case of poisoned fluid food, the first process is to evapo- 

 rate the fluid to the consistence of an extract, after w^hich the 

 digestion in the muriatic acid is proper, followed by the same 

 lixiviation and application of the same re-agents, as in the case 

 of the solid organic mixture. Where the stomach and its con- 

 tents, or any of the other intestines are involved in the exami- 

 nation, we boil the fluid matters as above to an extract, and 

 having pursued the same course as above described, where the 

 anatomical investigations and symptoms of disease, indicate 

 poison as the cause of death, and the frequent vomiting or vio- 

 lent purging may have removed, all traces of it from the fluids, 

 and when our tests applied remain insensible of its presence. — 

 We then commence to look for small undissolved portions 



