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Various explanations of this phenomenon have been proposed by MM. de Beaumont, Fournet, and Durocher. They refer to M. Gaudin's experiments on the fusion of quartz, which show that silex, as it cools, has the property of remaining in a viscous state, whereas alumina never does.
In open air, where they are attacked by various destructive agents, few of the rock- making minerals are stable compounds except quartz, the iron oxides, and the silicate of alumina; and so it is to one or more of these comparatively insoluble substances that most rocks are reduced by long decay. Which produces a mantle of finer waste, frost or chemical decay? which a thicker mantle?
This was furnished by the patent compound known as "Toxement," which is claimed by the inventor to be a resinate of calcium and silicate of alumina, which generates a resinate of lime and a silicate of alumina in crystalline form. It is further claimed that each of these materials is insoluble in sodium chloride and sodium sulphate, 3% solution.
By the removal of the soluble ingredients of feldspar there is left the silicate of alumina, united with water or hydrated, in the condition of a fine plastic clay which, when white and pure, is known as KAOLIN and is used in the manufacture of porcelain.
When the blast is directed against them they at first form a cake of some compactness, probably in consequence of the fusion of impurities they contain. The mass withstands for a very long time the blast without further fusion; but a slow carrying off, or burning, occurs, and, finally, a small quantity of a glass-like residue is left, which, I suppose, is melted alumina.
They stirred this mixture, let it settle, then decanted it, and obtained a clear liquid containing in solution sulphate of iron and sulphate of alumina, the other matters remaining solid, since they are insoluble. Lastly, this liquid being partly evaporated, crystals of sulphate of iron were deposited, and the not evaporated liquid, which contained the sulphate of alumina, was thrown away.
ANALYSIS OF PERFUMED SCOURING PASTES. The analysis of No. 1 resulted in water and traces of myrbane oil, 3.66 per cent.; fatty acid, melting at 104° F., 54.18 per cent.; iron peroxide, 10.11 per cent.; silicic acid, 14.48 per cent.; alumina, 17.31 per cent.; lime and magnesia, traces. The iron peroxide is partly soluble in hydrochloric acid, the alumina entirely so as silicate.
Sumac or tannic acid, in combination with alumina, may be held to be equally inoffensive; now it is a fact that the great bulk of cotton goods are dyed with the aniline colors by the agency of these harmless chemicals.
Suppose, further, that a part of the intermediate area were raised to within two or three hundred fathoms of the surface for anything that we know to the contrary, the change of level might determine the substitution of greensand for the "chalk"; while, on the other hand, if part of the same area were depressed to three thousand fathoms, that change might determine the substitution of a different silicate of alumina and iron namely, clay for the "chalk" that would otherwise be formed.
The young student melted it and found that it would dissolve alumina. Then he ran an electric current through the melted mass, and there was a deposit of aluminum. This young man, just out of college, had discovered a process that resulted in reducing the cost of aluminum from twelve dollars a pound to eighteen cents.
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