344 Professor Bischof on the Origin of 
solution, capable of originating motion, or change of posi- 
tion, such as is implied in the conversion of an amorphous 
into a crystalline mass. 
_ Tus Oaks, AMBLESIDE, 
March 11. 1845. 
On the Origin of Quartz and Metalliferous Veins. By 
Professor GUSTAV BiscHoFr, of Bonn.* 
It is not possible that the quartz veins, in the various 
stratified formations—as in greywacke, in clay-slate, in horn- 
blende-slate, &c.—could have been formed by the agency of 
a smelting heat. Even presuming that it is in the power of 
nature to fuse quartz, which, taken alone, is infusible in the 
heat of our most intense furnaces, a mass of such excessive 
heat as molten silica must have fused the adjacent rock to a 
greater or less distance, according to the width of the quartz 
vein. Silicates must have been formed, much more fusible 
than the substance of the quartz vein. These silicates (fel- 
spar, mica, &e.), the bases for which (alumina, potash, soda, 
oxide of iron, &c.) had been furnished by the adjacent rock, 
must, however, have been found not only between the vein 
stuff and the rock, and far into this latter, but also pene- 
trating into the quartzose vein stuff itself; for, the consti- 
tuents of the adjacent rock, fused by the molten silica, would 
have penetrated into the interior of the vein stuff, and have 
formed silicates. 
Suppose only, for example, that molten silver is poured 
into a leaden mould, of such thickness that only that portion 
of the mould in the vicinity of the silver poured in should 
melt, there would not be found, after the cooling of the 
molten metal, a single particle of pure silver, but only a 
mixture of silver and lead. But the difference, in fusibility, 
between silica and rocks such as clay-slate, is certainly still 
greater than that between silver and lead; and the affinity 
of silica to the bases in the rocks, or the propensity of the 
latter to form silicates with the former, is certainly not less 
than the affinity of silver for lead. 
* Translated by Lewis D. B. Gordon, Esq., Professor of Civil Engi- 
neering in the University of Glasgow. 
