SPECIFIC GRAVITY. 
25 
1.65 specific gravity with the coal that sank. Each product was 
washed, air dried, and analyzed. 
The results are given in the following- table. Column 1 gives the 
percentage that the amount of coal in each grade of fineness forms of 
the entire sample treated; column 2, the percentage that the amount 
of coal in each class separated by gravity forms of the amount in its 
grade of fineness, and column 3, the percentage that the amount of 
coal in each class forms of the entire sample. Column 4 gives the 
determination of the ash in each class, expressed as a percentage of 
the amount of coal in the class; column 5, this determination of the 
ash expressed as a percentage of the entire sample of coal, and columns 
6 and 7 give the same percentages for the sulphur. The totals of the 
results for ash and sulphur, in columns 5 and 7, should obviously 
equal the ash and sulphur determinations, respectively, in the original 
coal, which are printed below them for purposes of comparison. The 
differences are due to unavoidable errors in the work and, in some 
cases, probably in part to the presence of sulphates extracted in 
washing. 
Impurities in co<d as related to different grades of fineness and classes of specific gravity. 
NO. 2023, BRAZIL NO. l.a 
Mechanical distribution of 
coal. 
Amount of ash in 
each class. 
Amount of sulphur 
in each class. 
Grade and class of coal. 
Per cent 
of entire 
sample 
in each 
grade. 
Amount in each 
class. 
As per 
cent of 
coal in 
the class. 
As per 
cent of 
entire 
sample 
of coal. 
As per 
cent of 
coal in 
the class. 
As per 
ccllt Of 
Per cent 
of its own 
grade. 
Per cent 
of entire 
sample. 
entire 
sample 
of coal. 
1. 
2. 
3. 
4. 
5. 
6. 
7. 
p, + rso 
3.95 
3, 05 
5 i. 43 
43. 57 
28. 64 
26.35 
11.64 
15 33 
30 22 
54.49 
1.131 
.804 
1.298 
.061 
. 967 
1.744 
1.90 
1.60 
.61 
.84 
.615 
5.41 
0.075 
Dust {80to40 
.049 
7.00 
Sum 
7.00 
18.10 
100. 00 
Fine, 40 to 10 
Specific gravity — 
Under 1.35 
62.11 
2. 23 
17.83 
17.83 
11.15 
.40 
3 20 
3.20 
.068 
1.35 to 1.45 
.003 
1.45 to 1.65 
.020 
Above 1.65 
.173 
100.00 
17.95 
30. 45 
Medium, 10 to 4 
Specific gravity— 
Under 1.35 
55. 53 
3.64 
28.01 
12.82 
17.55 
1.15 
8 85 
4 05 
13 90 
23. 38 
33 38 
55 08 
2.439 
. 269 
2. 954 
2.231 
.60 
.59 
.55 
8.92 
.105 
1.35 to 1.45... 
.007 
1.45 to 1.65... 
.049 
Above 1.65 
361 
Sum 
100.00 
31 60 
44.60 
Specific gravity— 
Under 1.35 
45. 10 
3.19 
31.92 
19.79 
21.20 
1.50 
15.00 
9.30 
17.33 
26 52 
32.74 
59.08 
3674 
.398 
4.911 
5.494 
.64 
.50 
.66 
21.24 
.136 
1.35 to 1.45 
.007 
1.45 to 1.65 
.099 
1.975 
Sum 
100. 00 
47.00 
IOC. 15 
Total 
103.55 
28. 375 
28.18 
3. 127 
4.28 
aSp. gr. of average lumps, 1.40; of selected lumps, 1.37. 
6128— Bull. 323—07—4 
