TKANSACTIONS OF SECTION B. 663 



The compound is miscible with ether and benzene. Both sodium chloride and 

 bromide were found in tlie residue in the flask. 



It is a curious fact that these substances cannot be completely burnt. If any 

 one of them is heated on platinimi foil in the Bansen lamp, it does not naelt, but 

 carbonises, and leaves a black siliceous residue which cannot be burnt white over 

 the blowpipe flame or even in a current of oxyt^en. But if the substance is treated 

 with a drop of pure strong siilphuric acid and now heated as before in the Bunsen 

 lamp, a pure white residue is obtained, which, by washing with hot water, leaves a 

 residue of pure silica. Nitric acid also acts in a similar manner. 



On account of this, the determination of carbon and hydrogen, in most cases, 

 could not be made, even with the help of lead chromate in oxygen. For the com- 

 position of these compounds we are therefore bound, unfortunately, to rely onthe 

 indications given by the silicon determinations, aided sometimes by the reactions 

 which these substances undergo on exposure to air. 



By exposing the previous compound to air it became solid, and was then in- 

 soluble m ether or benzene. It was washed with benzene and dried in vacuo over 

 sulphuric acid. It was of a dark grey colour, and as it was insoluble in the usual 

 solvents, an analysis of it was made, without further purification. 



The silicon determination had to suffice, and was carried out by heating the 

 substance on the water-bath with strong nitric acid, when a perfectly white residue 

 of silica was obtained. 



0-263 gr. subst. gave 0-150 gr. SiO„ = 26-6 % Si 

 Found. C^alc. for. (C^HJ, OSiO 



2G'6 % Si 24-1 % Si. 



But as it is scarcely conceivable that the bromine atoms can be so split off, 

 there is great doubt as to the existence of the above compound. 

 Tnmethylenesilicondichloricle, C;.H|,.SiC]^. 



r\ 



cir, sici, 

 cii/ 



This was prepared by mixing 10 grs. SiCl^ (1 niol.) with 11-88 grs. 

 CH2.Br.CH.,.CH,,Br (1 mol.) and diluting with dry ether. To this 5-4 grs. (2 mols.) 

 of sodium in fine condition and a few drops of acetic ether were added. The 

 number of molecules of either substance taking part in the reaction not being 

 known, excess of SiCl^ was at first used. The reaction began at once and became 

 so violent as to require cooling of the flask. Finally it was warmed on the water- 

 bath. The flask was now cooled and the liquid portion filtered ofl", and the greater 

 part of the ether removed by evapoi-ation. As a preliminary experiment showed 

 that the liquid decomposed by distillation, it was evaporated in vacuo over 

 sulphuric acid, as in the case of the ethylene compound. The liquid, which was 

 of a dark brown colour and became thick and fumed in the air, was immediately 

 placed in bulbs. 



0-23576 gr. subst. gave 0-217 CO., = 25-1 % C 

 0-103 H.,C) = 4-8 % H 

 0-271 gr. subst. gave 0-109 SiO, = 18-77 % Si 

 Found. "Oalc. for. OjHe.SiClj 



Si 18-77 % 19-85 % 



C 25-10 % 25-55 % 



H 4-80 % 4-25 % 



In the combustion a small residue of carbon was left. 

 The liquid is miscible with ether and benzene. 

 The reaction may be expressed as follows : — 

 CH..Br CH. 



r r\ 



CH„ +SiCl, + 2Na„ = CH„ SiCl, + 2NaCl + 2NaBr 



I 1/ ' 



CH,.Br CH/ 



