Gas lights. — igi 
a hens egg and placed in piles of thirty tons upon which 
water is thrown ; a spontaneous combustion takes place— 
sulphuric acid is readily formed, which takes hold of the 
iron—the piles continue hot until the mass is pulverized 
when it cools and is lixiviated. When the pieces of ore 
are large or the pile small, the sulphate of iron does not 
readily form. Boston is the principal market for the cop- 
peras. ; iis 
INTELLIGENCE AND MISCELLANIES. 
—— 
I. Forrien. 
Extracted and translated by Prof. Griscom. 
1. Crystallization of sub-carbonate of potash.—Fabronta 
chemist of Tuscany, states in the Annales de Chimie 
of January last, that, contrary to the opinion common- 
ly received, the sub-carbonate of potash, as contained 
in the potash of commerce, is capable of crystallizing. He 
evaporates the solution of common potash till it marks, 
while warm, the 53d degree of Baumés aréometer, when, - 
on cooling, all the foreign salts are precipitated. The li- 
quor Is then decanted and evaporated to the 55°. It is, 
at this point, slightly green, and has a penetrating alcaline 
odour. It is poured into a deep vessel, and crystals are 
soon formed in long rhomboidal plates, parallel and verti- 
cal, resting on the bottom of the vessel, while the upper 
ends are attached to a saline crust which covers the sur- 
face. Fresh crops may be successively formed by concen- 
trating the mother water to 55°, until the whole of the 
sub-carbonate is crystallized. By this means, he conceives 
a sub-carbonate of potash, quite pure, and of uniform pro- 
perties may be obtained. 
2. Gas lights.—Some interesting comparative results, 
relative to the illuminating power of coal gas and oil gas, 
are stated by Timothy Dewey in the Annals of Philoso- 
phy for December last. They were carefully drawn from 
experiments made of the gas, as it proceeded from the neigh 
