M. Wohler on a New Oxide of Silicon. 539 



is the part which silver and oxide of lead play in aqueous vapour 

 dissociated at 1000°. They absorb the oxygen ; and if simul- 

 taneously the hydrogen were removed, the decomposition would 

 continue until the complete saturation of the auxiliary bodies. 



In heating aqueous vapour as described in this memoir, an 

 effect is produced analogous to that of exposing a volatile liquid 

 to a current of gas, a vessel full of water in a current of dry air. 

 In the above experiment the carbonic acid carries away, while 

 the porous tube separates, the quantities of oxygen and hydrogen 

 which the tension of the dissociation of aqueous vapour at this 

 temperature produces. 



According to "Wohler*, when a mixture of chloride of calcium, 

 silicofluoride of sodium, and sodium are melted together, a 

 compound of calcium with silicium is obtained. This silicide 

 of calcium forms small cylindrical prisms which have the appear- 

 ance of graphite, and are of an iron-black colour with a semi- 

 metallic lustre. These prisms, like some crystals of mica, may 

 be split into small round discs. The body is unaltered by air 

 or water, but is violently attacked by hydrochloric acid with 

 a copious disengagement of hydrogen, and is changed into a 

 yellow substance without losing the form of the disc. 



The body thus formed appears to be a new oxide of silicon, 

 and has the following properties. It is of an intense sulphur- 

 yellow colour, and consists of small transparent lamina? : when 

 moist, it gradually becomes white in the air. Gently heated in 

 the air, it ignites, and burns with a luminous flame, leaving 

 silicic acid, which is coloured by amorphous silicon. Heated in 

 a tube, it disengages spontaneously inflammable siliciuretted 

 hydrogen gas, and leaves a mixture of silica and amorphous 

 silicon in dark-brown lustrous lamina). Treated with dilute 

 ammonia, it is converted into gelatinous silica, hydrogen being 

 copiously disengaged. With stong ammonia it ignites. Soda 

 acts in the same manner, while fluoric acid is without action. 



Hitherto the analyses have not given conclusive results, which 

 arises from the difficulty of obtaining the body quite pure. 



Linnemann has investigatedf the action of nascent hydrogen 

 on benzophenone, the ketone of benzoic acid. The material was 

 prepared by distilling benzoate of lime with lime, and the part 

 distilling between 290° and 325° taken for experiment. The 

 action of sodium-amalgam upon it is brisk, but little hydrogen 

 is liberated. After some time the soda formed diminishes the 

 energy of the action ; and this is removed by neutralization with 

 sulphuric acid and filtration from sulphate of soda, which is first 



* Liebig's Annalen, February 1863. f Ibid. 



