PROCEKDTXGS OF GEOLOCHC.VT, SOCIETIES. 
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pig-iron produced in various furnaces containins: a considerable portion of 
silicon, sometimes even as much as eight per cent., and frequently three 
or four per cent. The presence of it in iron modifies the properties of 
the latter considerably. It combines readily enough with copper. If we 
take a little copper or iron in a more or less' divided state, say in the form 
of filings, and mix tliese filings with common sand (a compound of sihcon 
and oxygen), and add an excess of charcoal, making a mixture of the 
three, and let the amount of charcoal and sand be such that, when we ex- 
pose the mixture in a crucible to a high temperature sufficient to melt the 
copper or the iron, as the case may be. there should be sufficient of this 
mixture to retain the metal diffused through the mass, and then expose 
the mixture to a high temperature for a few hours — all the silica, under 
the conjoined influence of the carbon and the metal, is decomposed, the 
carbon laying hold of the oxygen, and escaping in the form of carbonic 
oxide, while the silicon is set free, combining with the metal. Common 
copper treated in this way — heated with sand and charcoal for a long 
time — undergoes a great change in its external appearance. It has no 
longer the red colour of copper, but has the appearance of bronze, which 
is a mixture of copper and tin. It is so like the bronze of which our guns 
are composed, that an inexperienced eye would not distinguish the one 
from the other when they are side by side. It is a very valuable alloy, so 
that you see that silicon may play a very important part even in the 
common arts of this country. To give another illustration of the fusion 
of silica. Platinum is a metal which requires a very high heat for its fu- 
sion. If we heat silicon in contact with platinum at a high temperature, 
no change will take place ; but add a bit of charcoal, and repeat the expe- 
riment. The silica instantly becomes reduced under these conditions, and 
the silicon set free combines with the platinum, forming a very fusible 
compound. 
The lecturer added a few more words concerning the proofs — the mine- 
ralogical or geological proofs — relating to the aqueous origin of crystallized 
silica, and they are very conclusive. Let us look at our mineralogical 
cabinets, and examine the specimens of quartz which we find therein. One 
was exhibited, a very small one, which, when examined minutely, was 
found to surround a mineral called haematite, consisting of peroxide of 
iron and water — a mineral which loses its water at a very low temperature. 
There it was, embedded in the quartz, clearly showing that the quartz 
never could have been exposed to a high temperature. Here is another 
mineral, carbonate of iron, embedded in the quartz, and the existence of 
this and the peroxide clearly shows that that quartz never could have been 
exposed to a high temperature, and supports the conclusion at which we 
have arrived touching its aqueous origin. Then we find incrustations 
which lead to the same conclusion. 
With regard to amorphous silica, there is no doubt whatever about its 
aqueous origin. We can trace its origin in the clearest and most distinct 
way. In Iceland, for example, it is abundantly produced in the geysers. 
Here is a specimen which has been obtained from that source. Then, 
again, here is a specimen of granite from Iceland, on which is deposited a 
thin film of silica, having a pearly lustre. There is no one who will ven- 
ture to say that that could have been thrown down on to the granite 
except by the agency of water. The specimens are very small m them- 
selves, but, nevertheless, they speak very eloquently of the origin of sihca, 
and tell an important tale, small as they are. Here is a very characteristic 
specimen showing the occurrence of crystalhne quartz m two states on the 
VOL. VII. ^ 
