62 Royal Society » 



of this radical, which is formed by the action of sunlight upon iodide 

 of methyle and metallic mercury. After an exposure of several days 

 to sunlight, white crystals begin to form in the liquid, which finally 

 solidifies to a white crystalline mass ; ether dissolves out the new 

 compound and deposits it perfectly pure by spontaneous evaporation. 



Iodide of hydrargyromethylium (Cj H3 Hgl) is a white solid, 

 crystallizing in minute nacreous scales, which are insoluble in water, 

 moderately soluble in alcohol, and very soluble in ether and iodide 

 of methyle ; it is slightly volatile at ordinary temperatures, and ex- 

 hales a weak but peculiarly unpleasant odour, which leaves a nau- 

 seous taste upon the palate for several days. At 100° C. the vola- 

 tiUty is much greater, and the crystals are rapidly dissipated at this 

 temperature when exposed to a current of air. At 143° C. it fuses 

 and sublimes without decomposition, condensing in brilliant and ex- 

 tremely thin crystalline plates. In contact with the fixed alkalies 

 and ammonia it is converted into oxide of hydrargyromethylium, 

 which is dissolved by an excess of all these reagents. 



A corresponding compound containing amyle is formed, though 

 with difiiculty, under similar circumstances, but the attempts to form 

 one containing ethyle have not yet been successful. Preliminary 

 experiments have also been made with other metals, amongst which 

 arsenic, antimony, chromium, iron, manganese and cadmium promise 

 interesting results. 



From a review of the composition and habits of all the organo- 

 metallic bodies and their compounds at present known, the author 

 is of opinion that the view most generally held respecting the con- 

 stitution of cacodyle, according to which that radical is a conjugate 

 compound consisting of arsenic conjugated with two atoms of methyle, 

 and which view must, if true, be applied to all the organo- metallic 

 bodies, is no longer tenable ; and he contends that the behaviour of 

 these bodies clearly indicates that they are compounds formed upon 

 the type of the oxides of the respective metals, a portion of the oxygen 

 being replaced by the several radicals, methyle, ethyle and amylc ; 

 the establishment of this new view of their constitution will remove 

 these bodies from the class of organic radicals, and place them in the 

 most intimate relation with ammonia and the bases of Wurtz, Hof- 

 mann and Paul Thenard; indeed the close analogy between stibethine 

 and ammonia first suggested by Gerhardt, has been most satisfac- 

 torily demonstrated by the behaviour of stibethine with the haloid 

 compounds of methyle and ethyle. Stibethine furnishes us therefore 

 with a remarkable example of the law of symmetrical combination, 

 and shows that the formation of a five-atom group from one con- 

 taining three atoms can be efl^ected by the assimilation of two atoms, 

 either of the same or of opposite electro- chemical character : this 

 remarkable circumstance suggests the following question. Is this 

 behaviour common also to the corresponding compounds of arsenic, 

 phosphorus and nitrogen, and can the position of each of the five 

 atoms with which these elements respectively combine be occupied 

 indifferently by an electro-negative or an electro-positive element ? 

 This question, so important for the advance of our knowledge of the 

 organic bases and their congeners, cannot now long remain unanswered. 



