Prof. Berzelius's Method of Detecting Arsenic, $c. 131 



3. Account of Professor Berzelius's Method of Detecting Ar- 

 senic in the Bodies of Persons Poisoned. 



Professor Berzelius has lately given some instructions for 

 the discovery of arsenic in persons that have been poisoned 

 with it. He considers the reduction of arsenic to the metallic 

 state as the only incontestible proof of the presence of this poi- 

 son. Arsenic may occur in two ways, viz. when it is found 

 in substance (in the state of arsenious acid) in the dead body, 

 and when it is not found in this state ; though the intestines 

 of the dead body may contain it in the state of a solution. 



In the first of these cases, it is easy to determine the pre- 

 sence of arsenic. In order to do this, take a piece about 

 three inches long of an ordinary barometer tube, and having 

 drawn out one end of it C B, as shown in Plate I. Fig. 34. 

 into a much narrower tube, close the end B. Let some of the 

 arsenic found in the body be now put in at the open end A, 

 so that it may fall down to the end B. Any quantity of this 

 arsenic of sufficient volume to be taken from the body will 

 suffice for this purpose. The arsenic being at the end B, 

 a little charcoal is let fall upon it, after it has been freed from 

 all moisture by bringing it to a red-heat with the blow-pipe. 

 The charcoal is then heated in the tube at the flame of a 

 spirit-lamp, the point B being held out of the flame. When 

 the charcoal is very red, the point B containing the arsenic is 

 drawn into the flame. The arsenic is then instantly volati- 

 lized, and passing into vapour by the red charcoal, it is re- 

 duced, and reappears on the other side of the flame in a me- 

 tallic state. The flame is then brought slowly towards the 

 metallic sublimate, which is thus concentrated into a smaller 

 space in the small tube, and then presents a small metallic ring 

 shining like polished steel. * We have now only to verify, 

 by its smell, that the metallic sublimate is arsenic. For this 

 purpose, cut the small tube with a file a little above the sub- 

 limate', and, having heated the place where it lies, put the nose 

 above it at a small distance, and the particular odour of the 

 metal will be immediately perceived. 



* Had the experiment been made in the wide part of the tube, the re-, 

 suit would .scarcely have been visible with a small quantity of arsenic. 



