ON THE DECOMPOSING POWER OF HOT STEAM. 195 
and pure alumina, are intimately mixed, made into balls 
with water, and dried. These are placed in a tall, kiln-like 
furnace, protected as heretofore described, with an opening 
at the top for the introduction of the balls, and another at 
its base for their extraction, when the decomposition is com- 
pleted. A represents the body of the kiln ; C the fire- 
chamber, fed with coke or coal; D the door by which the 
charge is withdrawn from time to time as it is finished ; 
fresh additions being made at^the top so as to render the pro- 
cess continuous. The hot steam is admitted at B, where it 
mixes with the flame and heated air, and enters the inter- 
stices of the mass of balls conjointly with them, causing a 
uniformly moist atmosphere. The various precautions be- 
fore described, as to temperature, the proportion of steam, 
etc., must be observed in order to elfect the decomposition 
of the greatest proportion of the salt. Under favourable 
circumstances, seventy-five to eighty per cent, of the salt 
has been decomposed, though fifty per cent, can be effected 
with the greatest readiness. 
The balls, on removal, consist of aluminale of soda 
with excess of alumina. When lixiviated, the solution 
consists of caustic soda, holding in solution a large quantity 
of alumina, which is readily separated in a form suitable 
for the purposes of the dyer. 
Carbonate of soda (sal soda) is obtained at once bypass- 
ing carbonic acid through the alkaline solution, till the 
alumina is precipitated, decanting the clear liquid, evapo- 
rating, and crystallizing: — or it may be obtained by ex- 
posing the crushed balls to the action of the carbonic acid of 
the air for a month, when simple lixiviation and evapora- 
tion yields the alkaline carbonate. Professor Solly, states 
that for some purposes of the arts, the crude alkaline solu- 
tion may be employed at once, as in the manufacture of 
soaps. 
The experiments on a moderate scale, which have been 
made in London and Glasgow, under the superintendence 
