166 PRELIMINARY REPORT ON COAL-TESTING PLANT, [bull. 261; 
grains of lignite. The fresh briquettes were difficult to handle, and 
when broken open the grains of lignite seemed to be wet, as if coated 
with moisture, which prevented the pitch from adhering to them. 
Many of the briquettes were porous, not being sufficiently pressed, 
and they were also brittle. Some of them, however, were quite good. 
When broken up and burned in the stove they stood up in the tire 
very well and burned better than any lignite briquette that had thus 
far been made. They weighed on an average 6.31 pounds each. 
Another ton of this lignite was ground in the Williams mill and 
run through the drier, but this operation removed only a portion of 
the water, so that the briquette still contained considerable water. 
This material was briquetted on the English machine with 8 per 
cent of pitch H. A minimum amount of steam was used, which 
did not contain an}^ excess of water, and a maximum pressure was 
applied. As received from the machine, many of the briquettes showed 
perpendicular cracks due to the excessive pressure. The hot briquettes 
were difficult to handle, the individual grains of the lignite seeming to 
be wet and not cohering at all. Even under their own weight many 
of them would crack badly. On breaking open the hot briquettes thej 
grains of lignite seemed to move about as if they were alive. This lack 
of cohesion continued until the pitch became quite hard and could no 
longer be pressed in the machine. Thus the variation in the steam 
used as the mixture passed through the pug mill had no effect on the 
cohesion of the resultant briquettes. On cooling, however, these 
briquettes became very hard and strong and broke with a sharp frac- 
ture and with but a small amount of waste. In burning, these bri- 
quettes did not fall to pieces, as had been the case with the other lignite 
briquettes, but burned very satisfactorily. They were very light, 
weighing only 5.85 pounds each, and had a specific gravity of 0.98. 
The specific gravity of the coal was only 1.16. The crushing strength 
of these briquettes was 9,600 pounds to the square inch. 
Another ton of this coal was tested with a soft, tough asphalt, B6,l 
that was received from Casper, Wyo. As had been shown by labora- 
tory tests, this asphalt could not be used on the English machine alone, 
and as a result the lignite was briquetted with 5 per cent of asphalt 
B6, 2i per cent of rosin, and 1 per cent of lime which had previously 
been Irydrated. This mixture worked perfectly in the machine, anc 
the hot briquettes were firm and good and easily handled, but th( 
proportion of binder was not sufficient and the briquettes were dry 
and not strong. Another reason for this result was that during the 
two crushings and dryings of the lignite the grains had become of a 
nearly uniform size (about 10-mesh), so that the resultant briquettes 
were very porous in spite of the maximum pressure used. In burn- 
ing, the briquettes fell to pieces. They weighed on an average 5.10 
pounds each. A combination of this coal and asphalt can undoubtedly 
be obtained which will briquette satisfactorily. 
