150 PRELIMINARY REPORT ON COAL-TESTING PLANT, [bull.. 2KB 
pressure was relieved. Another ton of eoal with 8 per cent of pitch 
A contained too much binder, and another ton was made with 6 per] 
cent. These latter briquettes were compact and well pressed, but did 
not contain enough binder. Seven per cent of pitch A gave a better 
result than either 6 or 8. 
Another run of this coal was made with 3 per cent rosin and 2 pel 
cent of pitch A as a binder. The briquettes were very clean and shar 1 
in outline, but were somewhat brittle and had a tendency to break into 
large fragments. The} r were, however, physically better than those 
with 6 or 8 per cent of pitch alone. In burning, they held togethe 
very well, but smoked more than those with pitch alone, but no odo 
of rosin was given off. This same mixture was tested on the America 
machine, which gave clean, polished briquettes, which were stronge 
than those made on the English machine, indicating that rosin work 
to better advantage in the smaller and more rounded briquettes. 
A ton of this coal was briquetted by using 3 per cent of rosin and 3 
per cent of pitch A. This mixture made excellent briquettes, which! 
were usually clean and with sharp edges. It was also tried on the 
American machine and gave exceedingly smooth and lustrous eggettesj 
which were stronger than the large briquettes made on the Engl i sit 
machine. The eggettes were tested in a cook stove, where they burned 
very satisfactorily without any odor, but gave off considerably morii 
smoke than either coal or briquettes made from pitch alone as a binder 
This coal was further tested w r ith the softer pitch B, which was ooiMeai 
of the better pitches for briquetting. One ton was first made with U 
per cent of pitch, and the briquettes were clean, sharp, and apparentl 
considerably stronger than the original lump coal. These were thiflAr, 
first commercial briquettes made at the plant. They were capable ( 
standing very rough handling. In weight they averaged 7 pounc 
each, and their specific gravity was 1.17. On the American machiiilWi] 
this same mixture gave polished eggettes, but they were not so stroMjfe 
as those made on the English machine. Pitch B was then tried wi life 
rosin, the proportions being 95 per cent of coal, 3 per cent rosin, ai ||W 
2 per cent pitch. On account of the condensation of steam in the pi jj 
mill, there was considerable excess of water in the briquettes, whic 
however, were smooth and sharp when received from the press. ' T 
excess of moisture caused them to crack badly, and they were diffici 
to handle while fresh. After cooling, they were still soft, and th 
were noticeably inferior to the briquettes made with 3 per cent 
rosin and 2 per cent of pitch A. They weighed 7.2 pounds each. T 
mixture also was tested on the American machine, which made hare 
eggettes than the corresponding briquettes of the English machi: 
This is a further confirmation of the supposition that the smaller 8 
rounder form is better adapted for the rosin binder and will result i 
a harder and tougher briquette. 
