DETECTION OF ARSENIC. 125 



which may have attached themselves to the membranes of the 

 intestines. 



I shall not attempt to describe the appearances in the intes- 

 tines resulting from poisoning hy arsenic, as that duty may be 

 more ably discharged by the pathological anatomist, but pass 

 directly on to the chemical proceeding necessary to discover it. 

 The stomach or intestines must be cut up into small pieces, and 

 boiled for some time in distilled water, and the fluid filtered 

 off. The remaining animal matter may then be treated with 

 muriatic acid, and after disorganization is complete, the mass 

 must be lixiviated with the water which had been employed 

 to wash it, (the filtered solution above spoken of,) and then 

 commences the application of the usual re-agents as before 

 indicated. It will be readily seen that in all these cases the 

 general mode of proceeding is analogous. The object being 

 to bring the suspected matter into such a form as will render 

 the results of the tests decided and well marked. The process 

 recommended by Mr. Venables, is justly held in high esteem 

 by some chemists, and although I think that the course alrea- 

 dy indicated will prove satisfactory and efficient, I introduce 

 that of this gentleman, which varies somewhat from that we 

 have described. After having removed the organic matter, 

 and produced the sulphuret, he deflagrates that with nitrate 

 of potassa, which forms arseniate of potassa, dissolves the 

 product, supersaturates the liquid with acetic acid, precipi- 

 tates with nitrate of silver, and employs the arseniate of 

 silver thus formed for the reduction experiment. His reason 

 for preferring arseniate of silver for reduction being that it 

 parts with all or nearly all of its arsenic, while the sulphuret 

 only yields about a third. Christison considers this process to 

 be too much complicated to be generally successful, except 

 in the hands of a very expert operator. There are, perhaps, 

 never two cases requiring investigation presented to the che- 

 mist under precisely identical forms and circumstances. He 

 must, therefore, be guided altogether by general principles in 

 making his analysis, and the principle of the greatest conse- 

 quence, and to which he must give the strictest attention is 

 to reduce his subject to such a form as shall render the action 

 of his re-agents prompt, decided, and not liable to afford any 

 deceptive result in colour, form or density. This can most 



