ratt.] BR1Q0ETTING TESTS. 135 
orm, holding about 10 tons, from which it can be conveniently shoveled 
hrough a hole in the same floor onto a coal-feeding worm. At the 
ame time the pitch which is used as a hinder, having been first reduced 
o a suitable size, is fed into the pitch cracker, which reduces it to a 
Lalf-inch size and drops it to a smaller worm, and this in turn delivers 
t onto the coal in the larger worm. The smaller worm is driven by 
prockets from the larger one, and the percentage of pitch that is 
,dded to the coal can be varied by changing the wheels. 
While this arrangement gives good results when the same coal and 
)inder are used, it is not sufficiently flexible to he adapted to the differ- 
nces in behavior of the various coals and binders that were used in 
he experimental work; and therefore, for most of the experiments, 
he crushed coal and cracked binder were weighed out on Fairbanks 
cales and mixed by hand. The mixed coal and binder were then fed 
hrough the hole in the floor onto the larger worm. 
After a slight mixing in the larger worm, the material enters an 
mpact disintegrator, in which it is reduced to the desired degree of 
ineness. The speed of the disintegrator is varied according to the 
Character of the coal. This is accomplished by running either one or 
>oth sides of the disintegrator and by tightening or slacking the belts. 
from the disintegrator the well-mixed, finely divided mass is elevated 
o a pug mill, about 5 feet in vertical height, in which the pitch or 
>ther stiff binder is softened by contact with live steam. As there is 
10 attachment on this machine for introducing or utilizing superheated 
team, the range of temperatures in which the binder could be softened 
vas very limited. Then again, live steam is apt to be wet, and in such 
nstances it would often be a detriment to the production of successful 
Jpquettes. 
From the pug mill the plastic mixture falls by gravity to the feed 
>ox of the press, from which it is forced by a plunger into brass-lined 
nolds in a vertical revolving table. After a half revolution of the 
able the mass in the mold is heavily pressed by a system of combined 
evers, the pressure being limited to 2 tons per square inch by the 
ieldingof a stiff spring. This pressure, however, can be varied from 
few 7 pounds up to 2,000 pounds as a maximum. 
After another quarter revolution the briquettes are forced, by 
[leans of a plunger, out of the molds on a slide or table set at a con- 
enient height for stacking on trucks. In the experimental work at 
he plant the briquettes were taken from the slide or table by hand as 
oon as they were discharged from the press and stacked on a platform 
ust outside the building. The briquettes, as they come from the 
uachine, are rectangular, except for rounded corners, and weigh on 
he average 6.8 pounds each, the weight varying with the coal and 
inder used. The maximum capacity of this press is tons of 
riquettes per hour. 
