162 PRELIMINARY REPORT ON COAL-TESTING- PLANT, [bull. 26^ 
were hard, strong, and clean, being much better in eveiy way than 
any briquettes of this coal made with pitch D. They weighed on the 
average 6.25 pounds each and their specific gravity was 1.06. Their 
crushing strength was 13,050 pounds per square inch, nearly twice the 
strength of those made with 8 per cent pitch D. 
New Mexico No. *2. — This black lignite is almost identical with New 
Mexico No. 1. It was tested with 9.3, 10.5, and 12 per cent of pitch 
X, but in evei\y case the resultant briquettes were very crumbly and 
no positive results could be obtained. 
This coal was next tested with pitch D as a binder, one ton of the 
coal being briquetted with 7 per cent of pitch D. The resultant 
briquettes were very crumbly, gray in color, and had an earthy fracture; 
They were neither hard nor strong and were porous, although thi 
pressure was increased to the limit. There did not seem to be any 
difference in the resultant briquette, whether made with a low or high 
pressure. There was a large amount of grayish efflorescence thai 
came out on the briquettes almost immediately. They weighed on arj 
average 7 pounds each. The eggettes made from this mixture, although 
not so porous, had the same earthy appearance and fracture and graj 
color. 
Another ton of this coal was briquetted with 9 per cent of pitch 0. 
and there was an excess of pitch, as was indicated by the bluish coloj 
on the external surfaces, due to partial volatilization of the pitch. Or) 
account of an excess of steam, the briquettes were rather soft an 
received from the machine, and owing to the excess of pitch many oi 
them stuck together. Although they were better than those mad 
with 7 per cent pitch D, they were not commercial briquettes 
They weighed on an average 7.12 pounds each. This coal was ver 
dirty and contained considerable clay, and the same difficulties wer 
experienced in briquetting it with pitch as with the Indian Territor 
No. 6 coal. From the work that was done on this sample, it has bee J 
definitely proved that such dirty lignites can not be well briquette 
with any commercial percentage of pitch as a binder, unless per ha] 
it is a pitch made from petroleum, as pitch H. 
Five tons of this coal were briquetted on the American machim 
using 10.25 per cent of the Hoffman patent binder, consisting 
petroleum, rosin, and quicklime. These briquettes were not ve 
tough, but held together pretty satisfactorily when burned under t 
boiler. a 
NORTH DAKOTA. 
North Dakota No. 1. — This is a tough, woody, brown lignite, whi 
does not disintegrate very readity. In the first test the lignite 1 
not previously dried and was mixed with 10 per cent of pitch 
a For steam test see p. 82. 
