292 . ANNUAL REPORT 
the blast carrying the coal dust, partly through air supply doors in the 
kiln head and partly through the opening through which the clinker is 
discharged. Its supply is solely gauged by the appearance of the clinker, 
that is, as much or as little air is used as will produce the right kind of 
clinker, irrespective of the coal consumption. The burner has as many as 
three means of regulation available for controlling the burning process, 
namely, the speed of the kiln, the rate of feeding the mixture and 
the rate of feeding the .coal dust. In some plants the mixture 
feed cannot be regulated so as to insure a steadier output, thus 
compelling the burner to work up to a definite adjustment. This 
seems more satisfactory, as with three means of regulation an 
indifferent burner is liable to become confused and does not do justice to 
the kiln, though it cannot be denied that in the hands of an expert burner 
the best results are obtained with three means of regulation. With a 
rapid cement feed the burner, on the other hand, desires to be on the safe 
side by using plenty of coal, thus tending to use more fuel than is neces- 
sary. The proper temperature is gauged by the appearance of tne clinker 
as it passes down the kiln. 
Two means of adjustment have so far not been made use of to: 
any extent, namely, the regulation of the blast pressure and of the 
direction of the coal dust blast into the kiln. 
The first means imply the use of a higher pressure, which can be 
cut down as desired, or the use of a coal blast pipe with a steady pressure 
and an auxiliary air pipe which may be regulated to suit the various 
conditions. At the works of the Edison Portland Cement Co., high air 
pressure is employed, as high as 60 pounds to the square inch, the writer 
was informed. 
The second method of bringing in the auxiliary air has been strongly 
recommended by several cement men. In this case an air chamber is 
built into the head from which the air flows upward, impinging upon 
the stream of coal dust at an angle and thus increasing the volume of the 
flame from a narrow to a larger zone. 
In regard to the direction of the coal dust blast Dr. Valeur reports 
some interesting observations. In a kiln rotating in the direction of the 
hands of a clock the clinker rises on the wall of the left side of the kiln 
while the right side is practically bare. The blast was introduced at the 
left side of the kiln and assumed a rotary or gyratory motion. After 
striking the bare wall of the right side of the kiln it again returned to the 
left side. At the place where the flame strikes the bare wall of the kiln 
it softens the brick which, hence, when coming in contact with the 
clinker, are worn by abrasion and succumb very rapidly. This experience 
caused Dr. Valeur to adjust the angle of the blast so that it struck the 
left side of the kiln at a definite distance, 414 feet from the end, with 
