VOLATILE MATTER IN EUELS. 
43 
minutes' preliminary heating over a low flame, determinations were 
made upon these samples with and without additional moisture, with 
the following results: 
Determinations of volatile matter {percentages) after four minutes' preliminary heating, 
showing effect of loosely held moisture. 
Fuel treated. 
Volatile -matter determinations (by- 
modified method) in the presence of 
stated amounts of added moisture. 
No mois- 
ture 
added. 
0.15 
gram. 
0.2 
gram. 
0.3 
gram. 
30.35 
34. 85 
36.90 
31.65 
36.10 
37.40 
These results show that even with a gradual preliminary heating 
the presence of loosely held moisture increases the value of the vola- 
tile determinations, the difference in some of the samples being as 
great as the difference by the official method; from which it appears 
that the rapid application of heat sufficient to drive off this moisture 
results in a reaction between the water vapor and the carbon or hydro- 
carbons in the coal. 
The results of the foregoing experiments and tests show that the 
value obtained for volatile matter in coal is affected to an important 
degree: (1) By the method of heating the sample, (2) by the fineness 
of pulverization, and (3) by the amount of loosely held moisture 
present. In bituminous coals these differences do not exceed 3 or 4 
per cent, and appear to be entirely due to a different breaking up of 
the hydrocarbon compounds under the different conditions of heat 
treatment, fineness of sample, and amount of moisture present. In 
the case of lignites, where the difference may be as high as 25 per 
cent, this difference is largely due to the mechanical loss in the sample 
during the rapid expulsion of the volatile matter. 
In the routine work of the laboratory in making the determinations 
of volatile matter the official method is at present used for ordinary 
bituminous coals, while lignites or other coals with more than 10 per 
cent moisture are heated for four minutes at a low temperature and 
then for seven minutes over the full flame of the Bunsen burner. 
