22 
THE PURCHASE OP COAL UNDER SPECIFICATIONS. 
nor the purchaser will gain or lose by change in the moisture con- 
tent of the coal between the time it is weighed at the mine and the 
time it is weighed on delivery. The price per ton will be correspond- 
ingly lower if the coal is wet and higher if the coal is dry. 
In order to determine the maximum variation in moisture in sev- 
eral sizes of anthracite coal the following experiments were made: 
The coal was soaked in water to allow it to absorb as much moisture 
as possible, the result representing the extreme conditions due to 
rains or other causes. Each sample was then weighed and allowed 
to dry in a room exposed to the air. When this sample ceased to lose 
moisture it was assumed to be air dried, which represents the condi- 
tion of least moisture to be expected in a delivery of coal. The re- 
sults are summarized in the following table : 
Experiments to determine possible variations of moisture in anthracite coal 
during shipment. 
Furnace. 
Pea. 
Buck- 
wheat. 
13 
0.5 to 24 
5.12 
3.58 
.73tol.54 
30 
10 
24 
5.74 
1.84 
3.1to3.9 
68 
12 
Number of hours dried in air at ordinary room temperature 
24 
8.44 
Moisture in air-dried samples do 
Loss of moisture - do 
Percentage of maximum variation in moisture from wet to air- 
2.24 
4.5to6.2 
74 
The air-dried anthracite still contains from 1.8 to 3.6 per cent of 
moisture. Moisture in air-dried coal varies with the weather, just as 
it does in wood. 
The moisture in air-dried bituminous coals depends on the character 
of the coal. It is about 1 per cent in West Virginia coal and about 7 
per cent in Illinois coal. The moisture in the same Illinois coal 
delivered may range from 7 to 17 per cent. 
Owing to these variations some method should be used to correct 
for the difference in moisture in coals of different character. 
The following suggestions are presented for the guidance of those 
who wish to send samples to a laboratory for analysis : 
If samples are taken at the buildings as the coal is delivered, it will 
usually be satisfactory to take one shovelful of coal from each third 
or fifth wagonload, the load being selected without the knowledge of 
the driver. It must be kept in mind that the main object is to obtain 
a portion of coal which represents as nearly as possible the entire 
delivery. The sample should contain about the same proportion of 
lump and fine coal as exists in the shipment as a whole. The practice 
of taking a shovelful near the bottom of the pile should be avoided, 
as the larger lumps of coal roll down and collect near the bottom and 
such a sample will not truly represent the coal. 
