1904-5. | THE CHEMICAL INDUSTRIES OF THE DOMINION. 173 
horizontal. These rotary calciners are the great feature of the Canadian 
cement plants. This form of kiln is originally of English origin, but has 
only been brought to its present effective condition since its introduction 
to this country. In the interior of the kiln are ‘‘channel-irons”’ running 
from end to end. At the lower end fuel is introduced in a particular 
manner, and the burning gases pass through the entire length of the kiln, 
and are allowed to escape at the upper extremity. At this latter end is 
introduced the ‘‘slurry’’ of the mixed ingredients, which becomes dried 
and finally calcined in the slow passage from one end to the other. The 
revolving irons carry the ‘‘slurry’’ up with them as they rise, and on 
reaching the top it falls, under the action of gravity, through the burning 
gases, being subjected at the hottest part to a temperature of 3,000° F., 
when combination takes place between the constituents of the fused mass, 
and the resulting ‘“‘clinker’’ emerges into the vessel destined for its recep- 
tion. The drying and calcining is thus performed in one operation, and no 
preliminary pressing of the material into bricks is required.” At the works 
of the National Portland Cement Company, recently erected-at Durham, 
Ont., a great saving of time is effected by cooling the clinker in vessels 
drawn by an endless chain through a stream of water below the ground 
level. After cooling in this manner it is ground to a fine powder, and pack- 
ed in bags or barrels ready for use. The whole operation by this process 
occupies only eight hours, a period of time which will be appreciated by all 
acquainted with the older methods. At Durham the raw materials are 
brought from the natural deposits, which are close at hand, calcined, cooled, 
ground and packed by means of a continuous series of mechanical conveyers 
from one part of the establishment to the other. This company has an- 
other plant in course of erection at Hull, P.Q., on the Ottawa River, which 
is intended to supply the Eastern Canadian market. 
Several articles have appeared lately in the public press*® pointing 
out that a possible over-production of cement may be the result of the 
numerous large concerns which are already in operation or are about to be 
started. Whether or not this will take place in the immediate future 
depends, naturally, on the general prosperity of the country and the con- 
sequent demand for building materials. Certainly cement has gained 
considerable reputation as a substitute for stone, as can be seen by the 
extent to which it is made use of by architects. It can be readily moulded 
into any form and may then be dressed to represent the natural article. 
If it can ever oust stone and brick from their present position depends, 
not only on its comparative cost, but on the quality of cement put out by 
manufacturers. One case of a collapse due to an admixture of a single 
bag of inferior material and the whole fabric of the cement industry 
(47) The Portland Cement Industry: ‘‘Queen’s Quarterly,’ Jan. 1903. 
(48) ‘‘ The Globe,’ Toronto, March, 1903, and other papers. 
