* 
262 Scientific Intelligence. 
for the manufacture of sulphuric acid than the use of the 
lindr former described, but I prefer it for the two last men- 
ioned consider their bases the more important product 
of their > neuen nd the hydrates of these alkalies, and partic- 
state that of =. being fusible, would have much tendency to cor- 
ce interior of the cylin der, at the heat necessary to decompose 
the salts. I use a common reverberatory furnace, with its hearth cov- 
ered with a compact bed of native carbonate of magnesia, three or four 
inches thick. Several clay steam pipes are introduced through the roof 
of the furnace, so as to throw a current of heated steam over * the whole 
width of the hearth; these pipes are connected with a steam-boiler by 
a series of fire-clay tubes kept red hot. The sulphate, broken into pie- 
SF 
bonate of magnesia on the hearth of the furnace, and brought to a high 
red or low.white heat. A current of steam is then admitted from the 
aan through the red hot tubes, upon the charge. 
acid of the sulphate is carried off by the steam, and when I 
Big vomicoee it, the acid vapors are conveyed along with the gases 
of the fire, into a leaden chamber, to be combined into sulphuric acid 
The fs ea of Le and soda may to some extent be decomposed 
by being subjected at a high temperature to the action of a current 0 
steam, in the manner directed for the decomposition of the sulphate of 
baryta. But owing probably to the volatile nature of the bases of these 
salts ata high temperature, no large proportion of them can thus 
Of the large class of substances possessing these properties, which 
i convenience I will call combining substances, | prefer t o use either 
umina or the s subphosphat e of alumina. . The alumina is oan by 
enact igniting the sulphate of alumina, or by any other well known 
