J. M. Ordway on making Caustic Soda. 365 
caustic soda of fair quality should somehow be obtained directly 
from the crude soda lye, without the preliminary process of 
making a clear, desulphurized carbonate. But how this can be 
done economically, is a problem whose answer has not yet per- 
haps been reduced to the fewest possible terms. Yet the follow- 
ing process is but one remove from the greatest conceivable 
simplicity, while it has been found by actual working on the large 
scale to be sure and effectual, and so easy of execution that any 
_™man of good common sense can, by a few trials, acquire all the 
necessary experience. 
The “black balls” made in the usual manner are broken up 
The resulting carbonate of lime, after thorough draining, may 
“black balls.” 
Contained in the liquor. By a little practice one can soon learn 
to guess quite correctly at the quantity of oxyd required for any 
Particular kettle. There should be so much that when the mix- 
ture is dried down with constant stirring it may become a dry 
substance, and not fuse at a heat just below dull redness. 
ing this drying operation, ammonia is given off in abundance, 
resulting perhaps from the breaking up of the cyanids commonly 
Present in crude soda. Peculiar, but slight and not unpleasant 
odors, also arise from the decomposition of the organic impurities 
of the water used in lixiviation. At last when the water is all 
driven off, the mixture rapidly absorbs oxygen, and from a black 
or dark brown becomes rust colored throughout. The fire‘is 
now smothered and the roasted product, after standing in the 
kettle an hour or two with an occasional stirring, is thrown out 
into a clean iron vessel. As soon as the kettle is cold enough to 
be in no danger of cracking, it is filled again with a fresh charge, 
es excepting these intervals of cooling, the work is continu 
‘at and day without intermission. : : 
he rust Scdanall powder, when a sufficient quantity has aes 
mulated, is treated with hot water so as to get a solution — ng 
at about 30° B. This liquor, after standing till it has become 
perfectly clear, is drawn off and boiled down, by successive gra- 
