190 ON THE DECOMPOSING POWER OF HOT STEAM. 
Stirred in the interim, to effect its uniform oxidation. The 
atmosphere is kept in an oxidizing state by the admission 
of sufficient air directly into the chamber, and the heat is so 
regulated as not to cause even incipient fusion, the charge 
being kept in a porous state. When the usual examination 
shows the proper quantum of alkaline chromate, the charge 
is withdrawn and lixiviated with water. 
Improvements in the manufacture of certain acids, 
alkalies and alkaline salts. — The patentee claims the right 
to make certain acids, alkalies and alkaline salts, by expos- 
ing at a high temperature certain salts containing such acids 
and alkalies to the action of aqueous vapour, by which the 
acid is carried off, and the alkaline base either remains free 
or enters into combination with some third substance pro- 
vided for that purpose. To obtain sulphurous and sulphu- 
ric acids, sulphate of lime is preferred, and the operation is 
thus performed. A fine clay cylinder of close texture, and 
any convenient size, is placed vertically in a furnace, and 
provided with openings at to^ and bottom, for charging and 
discharging, which openings are capable of being closed 
air tight. To the top of this cylinder a fire clay escape 
tube is adapted for conveying off the acid vapours, and to 
the bottom, for the admission of steam, another clay pipe 
is adapted, connected with a steam boiler by a series of fire 
clay tubes. In order to diminish the corrosion of the cylin- 
der by the sulphate of lime or the lime itself, it is lined with 
a coating of native carbonate of magnesia, applied in a 
similar manner to the usual clay linings of chemical fur- 
naces. The cylinder is filled with pieces of sulphate of 
lime one-fourth of an inch in diameter, and having luted 
the openings, the cylinder and its contents are raised to a 
high red heat, and steam is passed from the boiler through 
the red hot clay tubes into the bottom of the cylinder, and 
up through the charge. The heated steam, in its passage 
through the sulphate of lime, carries off the acid in the state 
of sulphurous acid and oxygen, with sometimes a little sul- 
