253 Dr. E. Frankland on a New Series of 



I have not yet further examined the reactions of this remarkable 

 body, nor have I attempted the isolation of the hydrargyrome- 

 thylium. 



A cori'esponding compound containing amyle is formed, though 

 with difficulty, under similar circumstances, but I have not yet 

 succeeded in producing one containing sethyle, the iodide of this 

 radical yielding, as I have shown*, when exposed to sunlight in 

 contact with mercury, iodide of mercury, and a mixture of sethyle, 

 hydride of sethyle and olefiant gases. 



I have also made some preliminary experiments with other 

 metals, and find that most of them are capable of thus entering 

 into combination with the organic groups, methyle, sethyle, and 

 amyle ; amongst those which thus combine under the influence 

 of light most readily, and seem to promise the most interesting 

 results, I may mention arsenic, antimony, chromium, iron, man- 

 ganese and cadmium. 1 hope to have the honour of laying 

 before the Royal Society, at an early period, the results of my 

 experiments upon these compounds. 



Imperfect as our knowledge of the organo-metallic bodies may 

 yet appear, I am unwilling to close this memoir without direct- 

 mg attention to some peculiarities in the habits of these com- 

 pounds, which promise at least to throw some light upon their 

 rational constitution, if they do not lead to extensive modifica- 

 tions of our views respecting chemical compounds in general, 

 and especially that interesting class termed conjugate compounds. 



That stansethylium, zincmethylium, hydrargyromethylium, &c. 

 are perfectly analogous to cacodyle there can be no reasonable 

 doubt, inasmuch as, like that body, they combine directly with 

 the electro-negative metalloids forming true salts, from which, 

 in most cases, and probably in all, the original group can be 

 again separated unaltered, and therefore any view which may be 

 taken of the new bodies must necessarily be extended to cacodyle. 

 The discovery and isolation of this so-called organic radical by 

 Bunsen was certainly one of the most important steps in the 

 development of organic chemistry, and one, the influence of 

 which upon our theoretical views of the constitution of certain 

 classes of organic compounds, can scarcely be too highly esti- 

 mated. It was impossible to consider the striking features in 

 the behaviour of this body, without finding in them a most 

 remarkable confirmation of the theory of organic radicals, as pro- 

 pounded by Berzelius and Liebig. 



The formation of cacodyle, its habits, and the products of its 

 decomposition, have for some time left no doubt of the existence 



* Journal of the Chemical Society, vol. iii. p, 331. 



