FIELD WORK. 17 
INSPECTION PROCEDURE. 
In collecting the samples to be shipped to the plant, an inspector visits the mine and 
carefully examines the coal throughout its extent. He sees that the coal loaded for testing 
purposes fairly represents the average product of the mine; that when screened coal is to 
be sent, the size selected is available to the consumer and adapted to the purpose for which 
it is to be tested. Therefore, his first duty is to examine the screens and observe the 
method generally employed in separating the slate and other impurities from the coal 
while it is being loaded in the railroad car. He then enters the mine and notes carefully 
the character of the bed, the method of mining, and the amount of care taken by the miners 
to separate the shale partings and sulphur balls from the coal while loading it into mine cars. 
While the sample is being loaded into the railroad car the inspector stands inside and 
permits the slate pickers to discard only such material as is thrown off in the usual practice 
and as is consistent with the customary speed of loading. The material thrown out is 
afterwards examined by the inspector to determine why it is considered detrimental to the 
fuel value of the coal. When large amounts of slate, bone, iron pyrites, etc., have been 
discarded, the entire amount of refuse is weighed and noted in the inspector's report. 
Should the weight of this refuse exceed 2 per cent of the total weight of the sample of coal, 
the refuse is carefully sampled and analyzed. By this means an approximate idea of the 
reduction of ash and sulphur, due to hand picking, can be ascertained. 
MINE SAMPLES. 
Two or more samples for chemical analysis are taken by the inspector from working 
places in the mine. These analyses give the experts at the plant a definite idea of the 
quality of the coal before the practical tests are begun. They are also useful in showing 
the composition of the coal in its native condition; especially is this true of the moisture 
content. The object of the inspector is to secure a sample that will, as nearly as possible, 
represent run-of-mine coal. 
The analytical results from mine samples taken during the Exposition period (August to 
December, 1904) showed that some modification of the method then used was desirable. 
These changes have been made with the idea of determining more accurately the amount 
of moisture in the coal in its native condition and of eliminating as far as possible the per- 
sonal element, which figures so largely in all sampling where everything is left to the judg- 
ment of the sampler. 
Mine sampling as it is done at present by the inspectors of the fuel-testing plant consists 
of first making a careful study of the coal throughout the mine and observing what parts 
of the bed are discarded by the miner. Two or more places where the coal is of average 
development are then selected. These places are usually at widely separated points in 
the part of the mine from which most of the coal is being shipped. The face is then cleared 
of burned powder, loose coal, and dirt for 5 feet or so, and insecure pieces of the roof are 
taken down to prevent their falling into the sample. The sampler then spreads a rubber 
blanket on the floor of the mine close up to the face of the coal and makes a perpendicular 
cut from floor to roof, including everything in the sample but the parts of the bed discarded 
by the miner. He cuts sufficient coal to make not less than 5 pounds per foot in height — 
that is, a sample weighing not less than 30 pounds would be cut from a 6-foot seam of coal. 
When shale or other partings are to be included in the sample, great care is exercised in 
cutting them the full width and depth of the groove in order to preserve the proper pro- 
portion of coal and extraneous matter. When the required amount of coal is obtained 
a detailed record is made of the section of the bed from top to bottom, every perceptible 
parting and variation in the section being noted. The parts of the bed not included in 
the sample are clearly shown in this record, and from these notes the value of the sample 
may be judged. 
The cuttings are at once weighed and then sifted through a screen with a half-inch mesh. 
The remaining lumps are broken up in a portable grinding machine, and this process of 
screening and breaking is continued until the entire sample will pass through the screen. 
Bull. 290—06- 2 
