PROCESSES FOR THE CONVERSION OF CARBON INTO SILICON. 557 



an experiment which, however often successful, could not have established the 

 truth of that proposition. We did, however, repeat it once with 10 grains of para- 

 cyanogen, which were heated for three days in a small iron crucible. But on 

 opening it at the end of that time it was found quite empty.* 



Throughout our paper, we have taken for granted that what we have named 

 silica was really so. The body to which we give this name was a white powder, 

 which was occasionally soft when first produced, but invariably became gritty when 

 exposed for some time to a high temperature. In several cases it was as sharp 

 and gritty as builders' sand. It could be boiled for hours in aqua regia, or kept at 

 a white heat in a platina crucible for a similar period, without a perceptible loss in 

 weight. It bore the full blast of the blowpipe without change j and when fused 

 before it with carbonate of soda, formed a transparent bead. It dissolved in alka- 

 line carbonates with effervescence, and could be recovered from them by muriatic 

 acid unchanged in all its properties. Several of our specimens were fused in this 

 way again and again, without varying in their deportment from true silica. These 

 characters would suffice to prove the body possessing them silica, and completely 

 distinguish it from hydromellonic acid, or any other organic compound, which 

 might be supposed to be formed by the reaction of compounds of cyanogen on 

 alkaline carbonates. 



We were unwilling, however, to omit testing our supposed silica by its power 

 of forming fluosilicic acid when distilled with oil of vitriol and fluor spar. With 

 no little trouble we succeeded in providing ourselves with pure fluor, which was 

 ascertained, by repeated careful analyses, to be quite free from silica. The body 

 we were testing we distilled with the spar in a small leaden alembic, with its beak 

 dipping into water. The characteristic membranous tubes of silica formed rapidly, 

 and sank in gelatinous flakes to the bottom. After so decisive tests, we are quite 

 certain we were not mistaken in believing we had obtained silica. 



We may farther mention, that potassium heated with what we may now term 

 silica, liberated a black powder quite undistinguishable from the body it separates 

 from common silica. We may also add, that we ascertained the specific gravity of 

 the silica we obtained in our earliest experiments with ferrocyanide of copper. It 

 was 2'25 that given in the text books is 2'69. The difference is probably not 

 greater than that between different specimens of ordinary silica. 



In conclusion, we need scarcely say, that we have been unable to supply any 

 proof of the transmutability of carbon into silicon. The utmost we may have done, 



* When our paper was read, another repetition of this experiment was in progress, which has since 

 been completed. Twenty grains of purified paracyanogen were heated in an iron crucible for three days. 

 On examination, the powder was found so little changed in bulk and colour, that the lid of the crucible 

 was replaced, and the heating continued for three days more. A very pale brown powder was left, 

 amounting to 0'5 gr., which, when fused with carbonate of potass, left a trace of what appeared to be 

 silica. 



