Prof. Bunsen on Cacodyl Compounds containing Platinum, 395 



as is the case where nitric acid is employed. And as the de- 

 oxidized chromic acid, or the oxide of chromium formed, com- 

 bines with the sulphuric acid and potash immediately as it is 

 pi'oduced, no injurious effect can arise from diffusion between 

 the cells; the whole process goes on steadily and without in- 

 termission, until either the sulphuric acid in the zinc cell is 

 saturated with the oxide of zinc, or the whole of the chromic 

 acid of the bichromate is deoxidized. 



Various other arrangements, in which bichromate of potash 

 is used mixed with sulphuric, muriatic, nitric, and acetic acids, 

 with the usual, and also with different, metallic elements, are 

 under investigation ; and the results obtained, with their com- 

 parison with other batteries, will be laid before the Society at 

 an early period. 



LIX. On a nexo Class of Cacodyl Compounds containing Pla- 

 tinum. By Professor Bunsen of Marburg"^. 

 T N a former paper I have endeavoured to prove, from the 



numerous instances of substitution presented by alcarsin, 

 that this substance contains a ternary radical, composed of 

 arsenic united to a carbo-hydrogen (C4 Hg -|- AS2), and en- 

 tering into composition with elementary bodies like a metal, 

 in a manner not hitherto observed. This opinion has been 

 confirmed by my subsequent experiments, and may be consi- 

 dered of considerable importance in the question of compound 

 radicals. The chloride of this radical is reduced by those 

 metals which decompose water, at a temperature not exceed- 

 ing that of boiling water ; the free radical separating in the 

 form of a clear jethereal fluid, which oxidates in the air with 

 more rapidity than potassium, and produces two degrees of 

 oxidation by its combustion, namely, an acid and an oxide, 

 both of which can be again reduced by deoxidizing agents. 

 The analogy between cacodyl and the metals extends still 

 further ; for that radical unites directly with the non-metallic 

 elements, forming substances of the same nature as are pro- 

 duced when hydracids combine with the elements of metallic 

 oxides, water being produced. 



It will be seen, irom what has been said, that this substance 

 bears a greater resemblance than most other compound bodies 

 to ammonia. Under this impression I tried the action of 

 chloiide of platinum on it, and have been fortunate in ob- 

 taining a class of compounds analogous in composition to 

 those of Gros and Reiset; supposing the ammonia in the latter 



• Translated from the German MS. of the author by Dr. T.G.Tilley. Com- 

 iiiuiiicated by the Clicmical Society, having been read Dec. 7, 1841. 



