national importance, quite apart from what technical interest it may
possess.

The "ammonia-soda" process, which has played such havoc with the old
style of manufacture, proceeds on totally different lines. Briefly
stated, it depends on the fact that if a solution of salt in water is
mixed with bicarbonate of ammonium, under proper conditions, a
reaction takes place by which the salt, or chloride of sodium, is
converted at once into bicarbonate of sodium, the bicarbonate of
ammonium being at the same time converted into chloride of ammonium.

The bicarbonate of sodium settles out at once as insoluble crystals,
easily removed, marketable at once as such, or easily converted into
simple carbonate of sodium, and further into caustic soda, as in the
ordinary "old" process. The residual chloride of ammonium is
decomposed by distillation with lime, giving ammonia for reconversion
into bicarbonate of ammonium, and chloride of calcium, which is a
waste product.

The maker of "ammonia" soda works direct on the brine, as pumped from
the salt fields. His plant is simpler and less costly, and he arrives
at his first marketable product much more rapidly and with very much
lower working costs than the maker of Leblanc soda, in spite of all
the great mechanical improvements which have of late years been
introduced into the old process, and which have cheapened its work.

The original patents on the use of ammonium bicarbonate have, we
understand, long since expired. But the working details of the process
and much of the most successful apparatus have undergone great
development and improvement during late years, all the important