400 Prof. Bunsen on Cacodyl Compounds containing Platinum. 



of copper and copper-turnings, which last prevent any error 

 arising from iodine passing over. 



1. 2. 



Substance. . . 1-4322 1-146 



Carbonic acid 0-3745 0-300 



Water .... 0-2510 0-400. 



To estimate the iodine, 0-6685 of the salt, dried at 100° C, 

 was precipitated from solution by nitrate of silver, the preci- 

 pitate being afterwards boiled in nitric acid. This trial gave 



4232-62 100-00 



Sulphate of the Oxide of Cacoplatyl. 



To prepare this compound, a solution of 20 parts of the chlo- 

 ride of cacoplatyl, dried at 100° C, is boiled with 12-17 pans 

 of dried sulphate of silver till the solution is not rendered tur- 

 bid by salts of silver or chlorine. The filtered fluid is evapo- 

 rated in vacuo over sulphuric acid till crystallization begins. 

 At this degree of concentration a trace of the chloride of sil- 

 ver, which had remained dissolved, is precipitated. The chlo- 

 ride of silver is separated by filtration, and the solution again 

 evaporated ^?^ vacuo and over sulphuric acid, till the greater 

 part of the salt is deposited. The salt is purified by pressing 

 it between folds of bibulous paper. Thus prepared it has the 

 form of white hard crystalline grains, which appear, under the 

 microscope, to be prismatic. This salt is inodorous, but 

 possesses a bitter and astringent taste, which after a time sug- 

 gests a relation to the cacodyl compounds. It does not deli- 

 quesce, nor is it decomposed by contact with air. It may be 

 heated to 160° C. without injury; a few degrees higher its 

 colour becomes gray, then black, giving off vapours smelling 

 of cacodyl, and, lastly, it takes fire and burns like amadou, 

 leaving behind an arsenical compound containing platinum, 

 which is fusible. 



To ascertain the quantity of water contained in this com- 

 pound, 1-078 gramme was dried for 24 hours over sulphuric 

 acid, and then again for six hours at a temperature of 100° C. : 

 the loss of weight was 0-0045 gramme. By heating it for 

 three hours longer at 140° C. it lost 0*0025 gramme. It thus 

 appears that this compound parts with its hygroscopic water 



