tOS An Attempt to Analyse Silica. 



ner as the first experiment. When cold the silica was 

 found unaltered, pale, and almost white. The reguli were 

 rot so fully fused as in the former experiment, hut had 

 caked together here and there, in the form ot lumps. The 

 most globular reguli w«re selected and poli&hcd, and of 

 these ri5 grammes were dissolved in aqua rcgia. The 

 dissolution proceeded with great violence, and left t.ilica of 

 the form of the balls, of which some few were brown. 

 Aqua regia and the nitric acids are such sensible reagents 

 for carbon in silicated iron, that from the same iron where 

 muriatic and sulphuric acids leave a white earth, ihcy pro- 

 duce it brown, and sometimes, when the nitric acid is 

 used, black. The silica after ignition was snow white^and 

 retained the form of the iron. It weighed 0*225 of a 

 graiTinie, or about 19 per cent. 



c. Part of the reguli obtained in the foregoing experi- 

 ments were stretched out to thin laminae, and then dissolved 

 in aqua regia. The dissolution was vehement, and the acid 

 left a white mass of silica in the form of the laminae, which 

 swelled by a continued digestion, and, when the acid was 

 concentrated by evaporation, became semi-gelalini?ed. This 

 experiment proves that the malleal le iron mass was more 

 free from carbon than the unmalleable, and that it never- 

 theless contained the base of the silica, which therefore had 

 had no influence on its softness, which seemed entirely to 

 depend on the more or less complete deprivation of the 

 carbon. 



From these data, I formed the conclusion that silica is 

 by means of carbon reduced to a body, which enters into 

 union with iron, and which, not injuring the malleability 

 of the iron, must be of a metalline nature. 



In opposition to my conclusion, some affirm that the 

 silica is only u'echanically mixed with the melted iron. 

 As this opinion directly contradicts every notion that I can 

 form of the usual habitudes of melted metals with those 

 pulverulent bodies on which they exercise no chemical 

 affinity, I tried to cement the filings of iron with silica and 

 powder of charcoal, at a teinperature which could not fuse 

 the iron. The iron filings remained unaltered in point of 

 forin, but, on dissolution in muriatic acid, left as much as 

 6 per cent, of siliceous earth. 



d. In order to determine in some degree what quantity 

 of combustible siliceous base had been appropriated by the 

 iron in these experiments, I dissolved 3-5 grammes of sili- 

 cated iron in concentrated muriatic acid, and secured the 

 gas in an apparatus suitable for its combustion. The gas 



was 



