312 Researches on Artificial Production of Minerals. 
cherry-red, and, consequently, vastly below their point of 
fusion. 
Is it not likewise the same cause which appears sometimes 
to withdraw the quartz from the silicates or aluminates of 
the base; as in granite, when it envelopes crystals of cymo- 
phane, instead of having formed a double silicate like emerald 
and euclase ? : 
If mica still exhale by heat, fluorides of silicium and boron, 
or of lithium, dare we affirm that the granitic pastes did not 
likewise, at the time of their origin, enclose chlorides of sili- 
cium, boron, or aluminum; which are wanting, it is true, 
among the vapours now collected near volcanic orifices, when 
they are decomposed and precipitated by steam on coming 
in contact with the atmosphere, and where we see them not- 
withstanding contribute very probably to the formation of 
silicates, now attributed by the best observers to a product 
of volatilisation? Do we not still find, moreover, the chloride 
in considerable quantity in certain masses, such as the zircon 
syenite of Norway, and the rock of Ilmen (miascite), where 
this body is principally combined in eleolite, and where it ap- 
pears to have brought zirconium, tantalum, along with all 
the assemblage of rare elements which are the accompani- 
ments of these rocks ? 
It is by no means demonstrated that the presence of a cer- 
tain quantity of water should be, at high temperatures, an 
obstacle to such reactions, since we see silica and alumina 
become separate and anhydrous, from an aqueous solution at 
a temperature of from 300 to 400 degrees. And if, hitherto, 
experiments have referred principally to limited conditions 
of the different modes of formation, by the humid way and by 
the dry way, the same effect produced in these extreme cases, 
as the quartz and corundum, would perhaps sufficiently 
authorize us to conclude that it would likewise take place in 
intermediate conditions.—(Comptes Rendus de L’ Académie 
des Sciences, 1854.) 
