392 Professor Bunsen on the Radical of the Cacodyl Series. 



acid, it is soluble with decomposition. Red fuming acid occa- 

 sions oxidation with inflammation. Heated in the air, it 

 burns with an ash-coloured arsenical flame, without leaving 

 any residue. Heated in a glass tube, it gives out vapours 

 smelling of cacodyl, and deposits carbon, arsenious acid, , and 

 a ring of arsenic. The quantity produced from 100 grammes 

 of oxide amounted to a little above 0*5 gramme. From the 

 want of a sufficient quantity of this substance, I have only 

 been able to make one analysis, which I however trust is suffi- 

 cient, as every pi'ecaution was taken to ensure its accuracy. 



0'394 gr. of the dried substance was burned with oxide of 

 copper, and gave 0*1223 carbonic acid, and O'OY^ water. 



The arsenic was ascertained from the contents of the burning 

 tube. These were dissolved in nitric acid, the solution diluted 

 with water, and partly precipitated by carbonate of soda. 

 The solution filtered from the copper was perfectly free from 

 arsenic. The precipitate dissolved in hydrochloric acid, to 

 which sulphuret of soda was added, also produced no preci- 

 pitate of arsenic. The filtered solution gave, after being 

 boiled with sulphurous acid in the usual manner, 0-7191 sul- 

 phuret of arsenic ; of which 0"633S, acted upon by nitric acid, 

 gave 0'0528 sulphur, and 2*1566 of sulphate of barytes. The 

 following are the results : — 



3500*88 100*00 100*00 



The difference of one per cent, in the arsenic found is ac- 

 counted for from a small quantity of sulphuret of copper 

 which was contained in the sulphuret of arsenic, which, on 

 account of its small amount, could not be ascertained. The 

 atomic weight of this substance I have not been able to ascer- 

 tain in a direct way, as it does not enter into any direct com- 

 bination ; but the probability is, from the relation it holds to 

 cacodyl, and to oxide of cacodyl, that that stated above is 

 correct. I have therefore shown that the radical of the ca- 

 codyl series is converted, at a temperature approaching to 

 redness, into marsh gas and oil gas, which gases may be con- 

 sidered as decomposing products of a non-isolated carburetted 

 hydrogen, C,, H^. From what precedes it also follows, that 

 of three atoms of oxide of cacodyl two atoms are decomposed 

 in the manner described, while one atom of erytrarsin is left 

 behind; — 



