12 
EXPERIMENTAL WORK IN FUEL TESTING. 
Results for moisture from coal wimples variously pulverized — Continued. 
Sample of coal. 
Labora- 
tory 
num- 
ber. 
2358 
2687 
2686 
2250 
2028 
2004 
2332 
2527 
2549 
2572 
2131 
3213 
3390 
Field number. 
Virginia No. 4 
Washington No. 1 A . . 
Washington No. IB.. 
West Virginia No. 4 B 
West Virginia No. 13 . 
West Virginia No. 14 . 
West Virginia No. 17 . 
West Virginia No. 18 . 
West Virginia No, 19 . 
West Virginia No. 21 . 
Wyoming No. 2 B 
Wyoming No. 5 
Wyoming No. 6 
Moisture in sample from — 
Bucking 
board. 
Per cent. 
2.35 
5.38 
4.55 
1.45 
1.10 
2.00 
1.15 
1.29 
0.65 
1.43 
4.57 
5.61 
8.90 
Ball mill 
Per cent. 
2.40 
5.98 
5.20 
J. 35 
1.17 
2.05 
1.00 
1.28 
0.68 
1.50 
4.65 
6.00 
8.68 
iV-inch 
mesh 
sieve. 
Per 
cent. 
2.28 
5.85 
4.65 
1.19 
1.15 
2. 05 
1.00 
1.13 
0.65 
1.44 
4.48 
6.04 
8.24 
Air of laboratory. 
Temper- 
ature. 
Humid- 
ity. 
Per cent. 
26 
24 
24 
69 
69 
50 
59 
37 
22 
24 
55 
The results for moisture obtained on the 5-gram portion of the 
coarse sample, as a rule, run from 0.1 to 0.2 per cent lower than the 
moisture value as determined upon the sample ground in the hall mill. 
In a few cases the moisture result on the coarse sample is somewhat 
higher than the result on the ball-mill sample, while in a few other 
cases, noticeably the lignite samples from California and Texas, the 
moisture result on the coarse sample is decidedly lower. This result, 
as shown by tests on sample 1680, California No. 1, may be ascribed 
to the fact that the moisture in a coarse sample of lignite is very: 
incompletely expelled by one hour's heating. An additional two hours 
of heating upon this sample resulted in an increased moisture value 
of over 0.7 per cent. As a method applied to any and all coals, the 
determination of the moisture in the fine sample appears to be prefer- 
able to the determination in the coarse sample. The results obtained 
for moisture upon the samples ground down on the bucking board, as 
compared with the results obtained on the samples ground down in 
the ball mill, show that the bucking-board samples may either gain or 
lose moisture, depending on the thoroughness of the preliminary dry- 
ing of the coarse samples and the humidity of the air in the laboratory 
at the time of sampling. For Illinois coals previously dried down to 
a moisture content of about 5 or 6 per cent, the bucking-board sample 
took up moisture during grinding when the humidity was high (70 
per cent or more). On the other hand, with low humidity (20 to 30 
per cent), the moisture loss during grinding was considerable, and a 
careful study of the results obtained upon the bucking-board sample, 
as compared with the results on the ball-mill sample, taken in connec- 
tion with the humidity changes, shows that any success in attempting 
to work the sample down on the bucking board without danger of 
moisture changes is practically impossible of realization, and that the 
sample ground down on the bucking board can not be in any case 
regarded as entirely satisfactory on account of the danger of moisture 
changes during the sampling. The experiments reported under the 
