TRANSACTIONS OF SECTION B. 661 



The refractive Indices are — 



For Lithium l-^TS 



„ Sodium 1-481 



„ Thallium 1-483 



Amyl pyro-ranadate is the only pyro- vanadate which I liave been able to 

 obtain in suiScient quantity for analysis. 



No meta-vanadates could be obtained, an ether and vanadium pentoxide always 

 being formed. 



AH these organic vanadates are immediately decomposed by water, with the 

 formation of vanadic acid, thus resembling the organic arsenates more closely than 

 the phosphates. 



As I was unable to prepare methyl vanadate, I tried the action of methyl 

 iodide on silver phosphate, and obtained methyl phosphate, a colourless liquid, 

 boiling at 190° C. (uncorrected). 



12. On some Organo-silicon Compounds. 

 By W. B. Hart, A.I.G. 



Prior to the year 1885, the general method of preparation of organo-silicon 

 compounds consisted in the use of an organo-metallic body, such as the zinc,' or the 

 mercuric - compound, with silicon chloride. In that year Polis ^ prepared aromatic 

 silicon compounds by the use of Michaelis's general method, which consists in the 

 removal of halogen atoms in a mixture of the halogen-organic compound and 

 silicon chloride by means of sodium, and a consequent linking of the residues. 



In every instance mono-halogen derivatives of hydro-carbons have been used, 

 and compounds containing monad radicals have been obtained. It was thought 

 interesting to attempt the preparation of substances containing dyad radicles by 

 the use of di-halogen deri^'atives. 



The method that Polis used was adopted, as being most suitable, and simplest 

 to carry out. It consists in bringing together the required amounts of silicon 

 tetrachloride and di-halogen derivative of the hydrocarbon, diluting with dry 

 ether and adding the calculated quantity of metallic sodium. 

 Dichlorsilicodiethjlenedibromide, 

 CH,.Br 



r 



^g^>SiCl, or (C.,H,Br).SiCl., 



CH.,.Br 



A mixture of 10 grs. CoH^Br,, (2 mols.) and 4-5 grs. SiCl^ (1 mol.) was diluted 

 with thrice its volume of dry ether, the whole being placed in a flask connected 

 with a reversed condenser ; and now 5 grs. of metallic sodium (4 mols.), in thin 

 slices, were added, together with a few drops of acetic ether. An action began, 

 and continued, but slowly, for some time. After standing four days in the cold 

 the liquid portion was filtered off, the ether removed by heating up to 100° on the 

 water-bath, and the remaining liquid now distilled. The chief part came over 

 between 1.30° to 1.34° as a colourless fuming liquid, which on examination was 

 found to contain silicon, together with chlorine and bromine. It burnt wath a 

 luminous flame. 



Analysis of halogens gave 



7-76 % CI. 31-48 o/o Br. 



The silicon was too small in quantity to be determined. 



The halogen determination was carried out as follows : — • 



The liquid, weighed out in a bulb, was placed in a closely stoppered bottle, 

 with excess of dilute NH^HO ; the bulb was now broken by shaking. The contents 



' Friedel & Crafts, Bull. Soc. CMm. [2] iii. 356. 

 - Ladenburg, Ann. Chem. Pharm. clxxiii. 151. 

 ' Ber. Beiitsch. Chem. Ges. Txm. 1540. 



