IN CASES OF POISONING. 259 



very careful examination of the contents of the stomach 

 and intestines, or of the vomited matters. The sub- 

 stances to be examined are spread out in new and clean 

 porcelain dishes, turned over with perfectly clean glass 

 rods or spatulas, and examined with the help of a lens. 

 The analyst should seek especially for small white 

 hard particles or grains of undissolved arsenious acid, 

 which may be carefully picked out with a pair of pin- 

 cers. These must be looked for especially in the folds 

 of the mucous coat of the stomach and intestines. By 

 stirring up the contents with distilled water, or better, 

 with spirit, and pouring off the lighter organic mat- 

 ters, it is often possible to separate a considerable 

 quantity of the heavy arsenic-powder. 



In a judicial investigation of this description, the 

 aim of all chemical operations is to obtain the arsenic 

 in its elementary solid state, as the so-called metallic 

 arsenic. In this form alone it is possessed of such highly 

 characteristic properties as to render it impossible to 

 confound it with any other substance, and to allow it 

 to be distinctly recognized even when in almost impon- 

 derable quantities. Moreover, all evidence of its pre- 

 sence is insufficient, unless it can be laid before the 

 tribunal in this form ; and all other forms and states of 

 combination must be considered as affording inconclu- 

 sive testimony as to the existence of arsenic in the 

 substance under examination. This preparation or 

 isolation of arsenic in its metallic state, even in the 

 smallest, almost imponderable quantities, is very sim- 

 ple and easy. Great difficulties, however, present 

 themselves, when it is necessary to extract these traces 

 of arsenic, which are diffused through a whole body, 

 from the great mass of organic matter, and to convert 

 them into some form of combination, from which the 

 arsenic can be extracted in the metallic state. 



It is most convenient, in considering the process 



