at a rate of evaporation of 50 to 55 tons per 24
hours under 90 lb. pressure. Deducting from this the 0.7 ton necessary
for working the plant leaves an available amount of steam raised by
the gas from one ton of fuel of 5.1 tons, equal to 75 per cent. of the
steam that we can obtain from the same fuel by hand firing.

In addition to the gas, we obtain about 3 per cent. of tar from the
fuel. This tar is very thick, and of little commercial value. It
contains only 4 per cent. of oils volatile below 200 deg. C., and 38 per
cent. of oils of a higher boiling point, consisting mostly of creosote
oils very similar to those obtained from blast furnaces; and only
small quantities of anthracene and paraffin wax.

I have made no attempts to utilize this tar except as fuel. It
evaporates nearly twice as much water as its weight of coal, and we
have thus to add its evaporative efficiency to that of the gas given
above, leading to a total of about 80 per cent. of the evaporative
efficiency of the fuel used in the producers. The loss involved in
gasifying the fuel to recover the ammonia therefrom amounts thus to 20
per cent. of the fuel used. This means that, where we have now to burn
100 tons of fuel, we shall have to burn 125 tons in the producers in
order to obtain ammonia equal to about half the nitrogen contained
therein. Our actual yield of ammonia on a large scale amounting on an
average to 32 kilos., equal to 70.6 lb. per ton of fuel, 125 tons of
fuel will turn out 4 tons of sulphate of ammonia. We thus consume 6.25
tons of fuel for every ton of sulphate obtained, or nearly the same
quantity as is used in producing a ton of caustic soda by the Le Blanc
process--a product not more than half the value of ammonium sulphate.
At present prices in Northwich this fuel represents a value of 35s. If
we add to this the extra cost of labor over and above the cost of
burning fuel in ordinary fireplaces, the cost of sulphuric acid, bags,
etc., we come to a total of 4l. 10s. to 5l. per ton of sulphate of
ammonia, which at the present selling price of this article, say 12l.
per ton, leaves, after a liberal allowance for wear and tear of plant,
an ample margin of profit. With a rise in the price of fuel, this
margin, however, rapidly decreases, and the working of the process
will, of course, be much more expensive on a small scale, as will also
be the cost of the plant, which under all circumstances is very
considerable. The great advantages