TBANSACTIONS OF SECTiON B. 567 



Section B.— CHEMICAL SCIENCE. 



President of the Section— Professor A. W. Williamson, Ph.D., LL.U., 



F.R.S., V.P.G.S. 



[For Professor Williamson's Address see next page]. 



THURSDAY, SEPTEMBER 1. 

 The following Report and Papers were read : — 



1. Report of the Committee on the Method of Determinwg the Specific 

 Refraction of Solids from their Sohdions. — See Reports, p. 155. 



2. 0?i a Process for Utilising Waste-products and Economising Fuel in the 



Extraction of Copper. By J. DixON. 



3. On Metallic Compo^lnds containing Bivalent Hydrocarbon Radicals, 



Part II. By J. Sakurai. 



In a former communication (' Brit. Ass. Report,' 1880) a new organo-mercury 

 compound was described, of which the interesting feature was the bivalent 

 character of the hydrocarbon radical contained in it, viz. methylene ; this being, 

 so far as I can ascertain, the iii'st body ever obtained of its class. 



The bivalent function of the organic radical, as well as of the metal, naturally 

 suggests the existence of another compound, similar to the first, but containing an 

 additional atom of mercury, thus : — 



1° I CHjHgl. 

 2° I HgOH„HgI. 



This second compound, which is related to methylene iodide in the same way 

 as mercuric iodomethide (CHjHgl) is to methyl iodide, can be easily obtained by 

 exposing a mixture of methjdene iodide, with an excess of mercury, to the action 

 of light. It is desirable to add a little mercuric iodide, so as to form mercurous 

 iodide, whose action has been fully^explained in the paper already referred to. It 

 is also necessary to add a sufficient quantity of ether, so as to keep the mixture in 

 the fluid condition, even towards the end of the reaction. The reaction takes from 

 one to several days, according to the state of weather and fi-equency of shaking. 



In order to get the compound in a state of purity the following plan was 

 adopted : — Ether is distilled off, and the residue is digested with a strong aqueous 

 solution of potassic iodide. It is washed, first with water containing potassic 

 iodide, and afterwards with pure water, till the washing is free from iodide, and 

 then dried. It is now heated with methylene iodide, whereby any excess of mercury 

 collects at the bottom of the beaker into a globule, leavijig above it a clear yellow 

 solution. The latter is decanted, and, on cooling, crystals are rapidly deposited ; 

 the first crops consist of pure di-mercury compound, whilst later portions and the 

 mother liquor contain the mono-mercury compound. The first portions are drained, 

 washed with methylene iodide, and then thoroughly with ether till a drop of the 

 washings rapidly evaporates without leaving any oily residue. 



Di-mercury methylene iodide thus obtained is a yellowish crystalline powder 



