WASHING TESTS. 9 
after washing. Owing, however, to the fact that there were only t w< > 
sludge tanks — one for the washed coal and one for the refuse — only 
one jig could be operated at a time, since if two or more jigs were 
operated their output would become mixed in the sludge tanks. 
With the existing arrangement of the washery it was necessary to 
use the same water over and over again. The washed-coal sludge 
tank, supplied with water from the city mains, was used as a reser- 
voir from which the water was delivered, principally beneath the 
screens of the jigs. A considerable amount of fine coal was thus car- 
ried over from the sludge tank. The bulk of this fine coal settled to 
the bottom of the jig body, where it became mixed with the refuse 
and was carried on to the refuse sludge tank. 
All coals tested were passed through an 18 by 24 inch Cornish 
tooth-roll crusher, which breaks the coal down to a maximum size 
of about 2 inches, although, of course, a considerable proportion may 
be much smaller, depending on the nature of the coal. 
The power for operating the plant was furnished by a 12 by 16 inch 
Frost steam engine, belted to a main shaft from which the jigs and 
other machinery of the plant were driven. The steam for this engine 
was received from the' boiler section. 
PERSONNEL. 
The 1905 tests were made under the direction of John D. Wick. 
REPORT FROM JANUARY i, 1906, TO JUNE 30, 1907. 
EQUIPMENT AND OPERATION. 
On February 22, 1906, the washery plant was almost entirely 
destroyed by fire, and with it a few samples of coal that were on hand 
in the storage bins. The plant was immediately rebuilt, the former 
arrangement being followed throughout. 
From January 1 to December 15, 1906, one Stewart jig was used 
in making all the washing tests. During December, 1906, a special jig 
was installed. This jig was of the center-plunger type, i. e., the 
plunger was directly beneath the screen, and the upstroke of the 
plunger caused the pulsation. The plunger had no valves, but val\ es 
were arranged in the sides of the jig body to admit the supply water 
on the downstroke of the plunger. Cams and springs were used in 
such a manner that the plunger had a slow downward and a quick 
upward stroke. The screen of this jig was 4 feet wide by 5 feel long 
and was made of strips of No. 10 wire running lengthwise of the screen 
frame and set one-sixteenth inch apart. The length of the stroke 
was adjustable up to 4 inches. The depth of the coal bed was also 
adjustable. 
