its theoretical heating power can be
utilized in evaporating water. Being so free from all deleterious
elements, notably sulphur, it makes better iron, steel, and glass than
coal fuel. It makes steam more regularly, as there is no opening of
doors, and no blank spaces are left on the grate bars to let cold air in,
and, when properly arranged, regulates the steam pressure, leaving the
man in charge nothing to do but to look after the water, and even that
could be accomplished if one cared to trust to such a volatile
water-tender. Boilers will last longer, and there will be fewer
explosions from unequal expansion and contraction, due from cold draughts
of air being let in on hot plates.

"An experiment was made to ascertain the value of gas as a fuel in
comparison with coal in generating steam, using a retort or boiler of 42
inches diameter, 10 feet long, with 4 inch tubes. It was first fired with
selected Youghiogheny coal, broken to about 4 inch cubes, and the furnace
was charged in a manner to obtain the best results possible with the
stack that was attached to the boiler. Nine pounds of water evaporated to
the pound of coal consumed was the best result obtained. The water was
measured by two meters, one in the suction and the other in the
discharge. The water was fed into a heater at a temperature of from 60 deg.
to 62 deg.; the heater was placed in the flue leading from the boiler to the
stack in both gas and coal experiments. In making the calculations, the
standard 76 lb. bushel of the Pittsburg district was used. Six hundred
and eighty-four pounds of water were evaporated per bushel, which was
60.9 per cent. of the theoretical value of the coal. Where gas was burned
under the same boiler, but with a different furnace, and taking 1 lb. of
gas to be 2.35 cubic feet, the water evaporated was found to be 20.31
lb., or 83.4 per cent. of the theoretical heat units were utilized. The
steam was under the atmospheric pressure, there being a large enough
opening to prevent any back pressure, the combustion of both gas and coal
was not hurried. It was found that the lower row of tubes could be
plugged and the same amount of water could be evaporated with the coal;
but with gas, by closing all the tubes--on the end next the stack--except
enough to get rid of the products of combustion, when the pressure on the
walls of the furnace was three ounces, and the fire forced to its best,
it was found that very nearly the same result