522 Prof. Wohler on Siliciuret of Manganese. 



posed with hydrochloric acid exactly into chloride of magnesium 

 and siliciuretted hydrogen, the latter would have the formula 

 Si H^, thus— 



SiMg2 + 2HCl=SiH2 + 2MgCl,— 

 and might contain in one volume half a volume of silicon gas 

 and two volumes of hydrogen. But in the decomposition, oxide 

 of silicon was formed, the production of which might, however, 

 depend on a secondary process, and staiid in connexion with the 

 simultaneous occurrence of free hydrogen. 



The manganese which Brunner* obtained by i-eduction of the 

 fluorides and chlorides of sodium by means of sodium, was found 

 by that chemist to possess other properties than that reduced 

 from the oxide by charcoal ; and on examining a specimen pre- 

 j)ared by Brunner, Wohler found that it dissolved in hydrochloric 

 acid with difficulty, and left a residue of oxide of silicon ; and it 

 was hence probable that this difference in the properties depended 

 on the presence of silicon which had been formed by the action 

 of the fluorides on the substance of the crucible. Wohler has 

 madet a variety of experiments with the view of obtaining a de- 

 finite compound of silicon and manganese. 



A mixture of equal parts of fluoride of manganese, water-glass, 

 cryolite, and sodium, firmly pressed in a Hessian crucible, and 

 covered with a layer of a mixture of chloride of sodium and 

 chloride of potassium, and then heated m a furnace, yielded a 

 well-fused, hard and brittle regulus,the fracture of which had in- 

 dications of a lamellar crystalline aspect, but appeared to contain 

 no free silicon. It was much less readily attacked by acid than 

 was Brunner's manganese. Each piece became covered with a 

 crust of dense oxide of silicon ; and. the gas which escaped con- 

 sisted of hydrogen containing siliciuretted hydrogen ; for on 

 being passed through a gently heated tube, a beautiful mirror 

 of silicon was formed. This specimen contained 11"7 per cent, 

 of silicon. 



Another experiment made with a mixture of fused chloride of 

 magnesium and sodium, fluor-spar, water-glass and sodium, gave 

 a fine brittle regulus containing a few small cavities lined with 

 steel- coloured prismatic crystals. This siliciuret of manganese 

 contained 13 per cent, of silicon, thus nearly corresponding to the 

 formula Mn^Si, which would require 13-37 per cent. 



In two experiments made with sodium, chloride of manganese 

 and sodium, and silicofluoride of potassium without the addition 

 of fluor-spar, no manganese was obtained. In another experiment 

 a mixture of chloride of manganese, sodium, cryolite, and quartz 



* Phil. Mag. vol. XV. p. 112. 

 t Liebig's Annaltn, April 1858. 



