elevators and conveyers.

(7) Improved quality of the cement, from non-mixture with
fuel, ash, or other impurities, and no overburning or
underburning of the material.

(8) Thorough control, from the facility of increasing or
diminishing the flow of crushed slurry and of regulating the
heat in the furnace as desirable.

(9) Absence of smoke and deleterious gases.

It is well known that in some localities the materials from which
Portland cement is made are of such a powdery character that they have
to be combined or moulded into balls or bricks previous to calcination
in the ordinary way, thus entailing expense which would be entirely
obviated by the adoption of the patent revolving furnace, as has been
proved by the author in producing excellent cement with a mixture of
slag sand from the blast furnaces of the Cleveland iron district, with
a proper proportion of chalk or limestone, which, in consequence of
the friable nature of the compound, he was unable to burn in the
ordinary cement kiln, but which, when burnt in the revolving furnace,
gave the most satisfactory results. The cement so made possessed
extraordinary strength and hardness, and it has been a matter of
surprise that iron masters and others have not adopted such a means of
converting a waste material--which at the present time entails upon
its producers constant heavy outlay for its removal--into a
remunerative branch of industry by the expenditure of a comparatively
small amount of capital. The demand for Portland cement has increased
and is still increasing at a rapid ratio. It is being manufactured