SBA An Attempt to analyse Silica, 



oleaginous mass had been for the most part dissipated 

 by boiling. The quantity of carbon is therefore 0O9&5. 

 The solution of iron oxygenated with nitric acid yielded 

 13-745 grammes of red oxide of iron*, answering to 953 

 grammes of iron. The water employed in washing had a 

 faint blueish colour, owing to some copper which, notwith- 

 standing a careful separation with the magnet, had adhered 

 to the iron filings. When evaporated to dryness and ignited, 

 the saline mass left a gray brown substance weighing 0-03 

 of a gramme, from which muriatic acid extracted 0-01 oxide 

 of copper, corresponding to 0*008 of copi)er. The re- 

 mainder was silica 0*02 {jr., which wiih that before obiained 

 gives 0'665 of silica. Jf now we add the iron to the car- 

 bon and the cojipcr, the sum will be 9-33 +0-0983 + 0-008 

 = 9 6365. The deficiency 0-3635 of a gramme must be base 

 of silica, which had afforded 0-665 of a eramme of silica. 

 Silica according to this experiment consists of 54*66 base, 

 and 45-34 oxygen. But, as we have here a manifest loss 

 of carbon, ihe result cannot be decisive; and if we assume 

 that the iron on an average contaiiled 0-OliJ of its weight 

 ot carbon, (reckoned according to the proportions between 

 the quantity of carbon obtained when the gas from dis- 

 solved cast-iron is burnt, and that which the iron by ex- 

 periments is found to contain, and which hereafter will be 

 described,) then the quantity of base will be 51-5, and of 

 oxygen 49'5. 



J. I tried to bruise a part of this silicated iron in a cast- 

 iron mortar, in order that I might afterwards burn it in 

 fusing nitre, as in the analysis of cast-iron, to find out the 

 whole charge of carbon; but it was too ductile to be pul- 

 verized. Nevertheless, mixed with nitre, I heated it in an 

 apparatus like that described for the analysis of the cast- 

 iron, but no carbonic acid was disengaged ; and when, 

 after an ignition of three hours, only a small quantity of, 

 oxygen gas was obtained, \ discontinued the experiment. I 

 dissolved the mass in water, which produced with lime water 

 no sign of precipitation. The iron had blackened on the 

 surface, but was in other respects unaltered. Since in this 

 manner it was impossible to acquire certainty respecting 

 the quantity of carbon, I now endeavoured to obtain a 

 carburet of cast-iron, by means of iron filings free from 

 copper, mixed with double its weight of silica and powder 

 of charcoal. This was expected to contain no malleable 

 iron; but I found that this also would not admit of being 



* Dissolved in muriatic acid, it left scarcely perceptible traces of silica in 

 8 half gelatiaated state, 



pulverized 



