390 Professor Bunsen on the Radical 



1 . 2. Calculated. 



Volume of the gas .... 1*4 I'S 1^ 

 Oxygen gas consumed . . 3*5 S** 3*5 

 Carbonic acid formed ... 2-0 2-0 2-0 

 These trials exactly agree with a compound in which the 

 combination with the carburetted hydrogen in the cacodyl 

 gives 4 volumes of vapour of carbon, 



12 volumes of hydrogen, 



condensed into 6 volumes. 



I was at first induced to suppose that a similar decomposi- 

 tion of cacodyl took place as in the case of cyanide of mer- 

 cury, as the action of this gas with chlorine did not agree with 

 the action of any of the compounds from which this mixture 

 of gases could in any manner arise ; but the uncommon con- 

 densation, the essential circumstance in this case, appeared 

 little to support this view. 1 have therefore continued the 

 examination, and found that the burning with chlorine arises 

 from the presence of a small quantity of a volatilizable com- 

 pound of arsenic, which does not separate from the mixture, 

 and which is at the same time the cause of the small stain of 

 arsenic, which, on burning this gas in oxygen, remains on the 

 side of the eudiometer. The true nature of this gas, given 

 out by heat from cacodyl, is shown by the action of fuming 

 sulphuric acid. This absorbs nearly one-third, and leaves 

 behind an inodorous gas, burning pale blue, which is not al- 

 tered by chlorine in the dark : in the 'direct rays of the sun, 

 however, as Melsens has shown of the gas of the acetates and 

 of marshes, it is condensed into oily camphor-like odorous 

 bodies, in the state of small white radiating crystals. From a 

 eudiometrical analysis of this gas, it appeared to be pure 

 marsh gas. I found 



From the volume examined . . . 19*2 



Oxygen consumed 41'1 



Carbonic acid formed 21*8 



There can, therefore, be no doubt that the carburetted hy- 

 drogen, C4 Hg, formed on the decomposition of cacodyl at a 

 high temperature, is not separated as such, but that there are 

 formed under these circumstances, two volumes of marsh gas 

 and one volume of olefiant gas, viz. 



C4 He As2 = ^ C, H, 

 lAs2 ^ 

 The examination of the gas not absorbed by the sulphuric 

 acid confirms this view of the question ; as one volume and a 



