Proceedings of the 'Royal Society* ^9* 



1. Silicon may be obtained from unconibincd paracyanogen. — When 

 paracyanogen, prepared from bicyanide of mercury by lieat under pres- 

 sure, as described in his former paper, was subjected to prolonged heat 

 in a closed tube of German glass, a dark-brown substance was obtained 

 which presented all the diagnostic characters of silicon. More especially 

 it was incombustible before the blow-pipe, underwent no change on be- 

 ing projected into fused chlorate of potash, but dissolved with efferves- 

 cence in fused carbonate of potash, forming a white saline substance, 

 in which silica was detected by its ordinary reagents. The same ex- 

 periment was performed with the like result on a larger scale in a por- 

 celain crucible ; and the quantity of silicon produced came within a very 

 small amount of the carbon contained, by theory, in the paracyanogen 

 employed. When paracyanogen is heated with carbonate of potassa, 

 silicic acid is obtained at once. A variety of experiments were described, 

 the purpose of which was to obviate all fallacy that might be supposed 

 to arise from silica being present in the vessels employed. 



^. Siliciurets may be obtained by the reaction of paracyanogen on 

 metals — When bicyanide of mercury was heated in tubes of copper or 

 iron in the way followed for obtaining paracyanogen, the interior of the 

 tubes was found to be lined with scales, which consisted, not of paracy- 

 anide or carburet of these metals, but of their siliciuret. And when 

 paracyanogen was heated in a platinum crucible several times in suc- 

 cession till the crucible would absorb nothing more, a compound was 

 obtained which was a siliciuret of platinum, containing four per cent, 

 of silicon. 



3. When paracyanogen is decomposed in the preceding experiments, 

 the nitrogen given off corresponds with what is contained by theory in 

 the compound which yields it. A variety of experiments of analysis 

 were mentioned to this effect ; from which a farther corroboration was 

 derived of the conclusion deduced from the author's previous researches, 

 that the silicon could come only from the-carbon of the paracyanogen. 



4. A siliciuret may be obtained from the paracyanide of iron. Under 

 this section, the author first described the process by which a pure para- 

 cyanide of iron may be obtained from ferrocyanide of potassium ; and 

 stated that he had found this compound to consist of one equivalent of 

 nitrogen, two of carbon, and one of iron. He then observed that he 

 had been led to suppose this compound to be the true compound radicle 

 of the so-called ferrocyanides ; on which subject ho proposed to make 

 ere long a distinct communication to the society. He next proceeded 

 to explain the results of numerous experiments on the influence of heat 

 on the paracyanide of iron ; from which it appeared that, under a high 



