PAPERS ON PHYSICS 291 
for 1 hour or longer; the fourth sample, McLean County, 
2nd seam coal, raised the temperature of the water only to 
200° F. Since this coal has a heat value of but 0.3 of 1 per 
cent less than that of sample No. 1, which boiled the water most 
quickly, the question arises, How are the remaining heat units 
in this coal expended? To answer this question experiment 
IT was snl 
ae 
ivesisss pineuitiisitaity 
CHARACT3R me THE COALS T2STe0, 
v 
20 Siftartcarten bon. Asn. 6.t.us. Boiled. 
No.1, 12.13% 58.93% 49.94% 7.89% 11,597 1 Hr.5 Min, 
Wo.2, 9.09% 34.55% 47.85% 8.55% 11,822 1 Hr.O Min, 
pi Wo.5. 11,278 42.216 37.7268 6.78% 11,55+ Did not boil, 
tt font, 7.05% 35.44% 49.01% 8.55% 12,341 1 Hr.5 Min, 
ae SOE 
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jualypes free Re niles doignentes! Study of Illinois 
Coals rof, 
7 
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3 
Fig. 1. Graph obtained from the 4th trial, Experiment 1. All four 
trials gave results approximately agreeing. 
EXPERIMENT II. 
The only modifications in Experiment II were the omission 
of the cover for the boiler and the use of but 60 pounds of 
water. The observations, however, were continued in this 
experiment for 12 hours for each trial. The graph (Fig. 2) 
shows the resulting temperature in the last one of three trials 
made with each sample tested. Only the first three samples, 
