504 BEPORT— 1880. 



greater wlien the number of water molecules was equal to the number of carbonic 

 oxide molecules, than when a fewer number of water molecules were present, and 

 their place taken by molecules of nitrogen, whose specitic heat is less than half that 

 of steam. 



4. On Metallic Compounds containing Divalent Organic Badicah. Part I. 



By J. Sakurai.i 



With the view of isolating metallic combinations of olefiant gas, Wanklyn and 

 "Von Than ('Jour. Chem. Soc' xii. 258) studied the action of mercury and zinc upon 

 ethylene iodide ; but they failed in obtainmg even a trace of organometaUic com- 

 pounds. I repeated their experiments not only with iodide and chloride of ethylene, 

 but also with the bromide and the chloriodide, and under various conditions'; but 

 the results obtained are essentially the same as those descrited by the above-named 

 chemists. _ Olefiant gas is given off in abundance, and metallic chloride, bromide, 

 or iodide is formed at the same time. 



At the suggestion of Professor "Williamson, methylene iodide was next tried ; 

 for it appeared probable that with this compound tlie" decomposition into metallic 

 iodide on the one hand, and into the hydrocarbon on the other, would be impos- 

 sible, or, at any rate, would not take place under such circumstances as those which, 

 while easily allowing the ethylene compound to decompose, are, at the same time, 

 favourable for, or essential to, the formation of organometaUic compounds. 



This anticipation was realised. By lea%-ing methylene iodide in contact with 

 metallic mercury and some mercurous iodide for a" few days, combination takes 

 place ^^-ithout any evolution of gas. One point of interest in" the reaction consists 

 in the part played by tlie mercurous iodide. This, under tlie influence of light, 

 decomposes into metaUie mercury and mercuric iodide: the former enters into 

 combination with metliylene iodidA ; and the latter, taking up fresh mercury, repro- 

 duces mercurous iodide ready for decomposition. 



Chiefly two products are formed. One of these, wlien properlv purified, is a 

 white crystalline substance, iusoluble in water, cold alcohol, ether, chloroform, 

 ethylic iodide, or benzene. It is somewliat soluble in Ijoiling alcohol, from which 

 it crystallises out, on cooling, in white slender needles. But by far the best solvent 

 for it is methylene iodide, whicli, when hot, takes up a considerable quantity of the 

 substance, and allows a part of it to crystalUse out on cooling. From the" mother 

 liquor, ether precipitates it almost completely in tlie form of fine crystals. The 

 substance melts at 108° to 109° C. to a clear yellow liquid, in which state it remains 

 up to a considerably higher temperature. On cooling, it solidifies to a yellow 

 crystalline mass, and re-melts at tlie original temperature. 



The following numliers were obtained on analysis : — 



I. 0-2075 gr. of the substance gave 0-1030 sv. of mercuric sulphide, 

 II. 0-0910 „ „ 0-0455 \, 



and 0-0910 „ silver iodide. 



Thus— 



Found. 



Calc for 



I. II. ('H,HcI. 



Mercury . . 42-790 43-100 42-735' 



Iodine ... — 54040 54-273 



Heated with iodine, the substance is decomposed into mercuric and methylene 

 iodide. Quantitative determinations show that for every 100 parts by weight of 

 the substance, 54-54 parts by weight of iodine are needed ; that is, as much iodine 

 as is contained in 100 parts of the substance. Now, if the compound contams in 

 its molecule nothing but a molecule of methylene iodide and an atom of mercm-y, 

 it ought to require, as_ it does, for the completion of the reaction, i.e. for the pro- 

 duction of methylene iodide and mercuric iodide, just as much iodine as it contains, 



^^"'■~ CH,IIgL + I, = CIIJ. + Ilgl,. 



Bromine and chlorine act upon the body in a manner similar to that of iodine. 



' Journal of Chemical Society, September 1880. 



