ow the escape of more
than 5 per cent. of the hydrochloric acid which he produces, or that
that acid must not exist to a greater extent than 0.2 grain in 1 cubic
foot of air, steam, or chimney gas which accompanies. The inspectors'
figures for last year show that the percentage of the acid which
escaped amounted to only 1.96 of the total produced, which is equal to
0.089 grain per cubic foot, and much below the figures for previous
years. The figures in regard to sulphurous gas are equally
satisfactory. The act allows 4 grains of sulphuric anhydride (SO3) per
cubic foot to escape into the air, and last year's average was only
0.737 grain, or less than a fifth of the limit.

Of course it is now the aim of the Leblanc alkali manufacturers to
reduce the escape of hydrochloric acid to the lowest possible amount,
as their profits depend solely upon the sale of chlorine products,
soda products being sold at a loss. In this connection it is
interesting to note that the amount of common salt manufactured in the
United Kingdom in 1888 was 2,039,867 tons, and of this nearly 600,000
tons were taken by Leblanc soda makers, and over 200,000 tons by the
ammonia-soda makers. The figures are very largely in excess of
previous years, and indicate a gratifying growth in trade.

The salt used in the Leblanc process yields the hydrochloric acid, and
that in the ammonia-soda method none, so that we may put down the
theoretical production of acid as 380,000 tons, 7,600 tons of which
was allowed to escape.

What was a mere trace in the chimney gases amounts, therefore, to a
good round figure at the end of a year, and if it were converted into
bleaching powder it would be worth nearly 150,000l. These figures are,
it should be understood, based on theory, but they serve to show to
what importance a gas has now reached which twenty-five years ago was
a perfect incubus to the manufacturers, and wrought desolation in the
country sides miles and miles around the producing works. There has
long been an expectation that the ammonia-soda makers would add the
manufacture of bleaching powder to their process, but they appear to
be as far as ever from that result, and meanwhile the Leblanc makers
are honestly striving to utilize every atom of the valuable material
which they handle. Hence the eagerness to recover the sulphur from
tank waste by one or other of the few workable processes which have
been proposed.

This waste contains from 11 to 15 per