ADAPTABILITY TO WASHING. 29 
certain of the coals, are given in the tables of results below. As these 
laboratory samples were all crushed to one- half inch and finer before 
testing, these results do not necessarily show what might be done 
with the coal crushed to other sizes. They do, however, give an indi- 
cation of the possible improvements which may be expected from 
washing. 
The u one-fortieth inch and finer" portion of the sample was tested 
as follows: The sample was stirred up with water, and after settling 
for one minute the liquid was decanted off very closely and the remain- 
ing portion was dried, weighed, and analyzed. The loss on decanta- 
tion indicates in a very general way the extent to which the coal 
breaks down into a fine powder upon handling or crushing, and is an 
indication of the amount of fine coal lost during washing. The par- 
ticular crushing machinery used would, however, greatly affect the 
amount of fines produced in crushing. The analytical results on the 
portion remaining after decantation are in a general way an index to 
the way the impurities separate from the coal in crushing. 
The interpretation of these results may perhaps be understood best 
by a consideration of the results derived from some particular sample, 
as Indiana No. 7 A. In this sample the ash and sulphur contents in 
the unwashed coal are, respectively, 0.03 and 3. 75. The sample crushed 
to "i inch to 4 J inch" was separated by sifting into 91.1 per cent 
coarse and 8.6 per cent fine. Considering the coarse portion: The 
part lighter than 1.35 specific gravity amounted to 86.7 per cent of 
the entire sample, and contained 6.69 per cent ash and 3.05 per cent 
sulphur. It is quite probable that in actual washing practice a large 
part of the " ±\ inch and finer" would be reduced in ash and sulphur 
contents to about the same percentage, which would indicate the pos- 
sibility of improving this coal 2 per cent in ash and 0.7 per cent in 
sulphur, accompanied by a washing loss of about 10 per cent. The 
distribution of the ash and sulphur on the heavier portion is shown 
by the percentage results on the "1.35 to 1.65" portion and on the 
portion u Heavier than 1.65." The washery tests do not show so great 
an improvement in ash and sulphur as might be expected from the 
analysis of the portion "Lighter than 1.35," and a portion of the "1.35 
to 1.65" specific gravity material evidently remained with the washed 
coal. However, washery tests upon such small lots of coal can not 
be expected to give the best results; also the possible improvement at 
i-inch size is apt to be greater than can be obtained at l^-inch size, at 
which the sample was worked at the washery. The results of the 
laboratory tests indicate that the high sulphur and the comparatively 
high ash in the washed coal from the washery is not the fault of the 
washing, but is due to the combination in which the ash and sulphur 
occur, showing that a very low ash and sulphur product can not be 
obtained from this coal by washing. The laboratory tests do, how- 
