METHODS OF SAMPLING AND TESTING. 23 
These samples should be immediately deposited in a metal recep- 
tacle having a tight-fitting cover and provided with a first-class lock. 
Except when samples are being deposited or when the contents are 
being quartered down, this receptacle should be securely locked and 
the key held by a responsible employee. The receptacle should be 
placed in a comparatively cool location to avoid loss of moisture in 
the coal. When it becomes filled, or at the end of the sampling 
period, the contents should be emptied on a clean, dry floor, in a cone- 
shaped pile. The larger lumps should be broken down by a coal maul 
or sledge, and the pile re-formed and quartered into four equal parts, 
a shovel or board being used to separate the four sections. Two 
opposite sections should then be rejected and the remaining two again 
mixed, broken down, and re-formed into a pile to be quartered as 
before. This process should be continued until the lumps are no 
larger than pea size, and a quart sample is finally procured. The 
samples should then immediately be placed in suitable receptacles for 
shipping and sealed air-tight. The Geological Survey inspectors use 
a metal can 3 inches in diameter and 9 inches high, with a screw cap 
2 inches in diameter, for making shipments to the chemical laboratory. 
These cans are sealed air-tight by winding adhesive electrical tape 
around the joint of the screw cap. Each can holds about a quart, or 
2 pounds of coal. 
The process of quartering down and preparing samples for ship- 
ment to the chemical laboratory for analysis should be carried on as 
rapidly as possible to avoid loss of moisture. The samples should 
be forwarded promptly and notice of shipment sent under separate 
cover. Receptacles should be marked plainly on the outside, and a 
corresponding number or description should be placed inside. A 
complete record of all deliveries should be kept, showing dates, 
names of contractor, kind of coal, total weight delivered, condition 
of coal (wet or dry), and any other particulars of importance. 
The procedure at the chemical laboratory of the Geological Survey 
testing plant is described in Survey Bulletin No. 261. The samples 
are crushed and ground to a fine powder, and then analyzed and 
tested. 
Persons not experienced in taking samples have a tendency to 
select a sample better than the average. In many cases a lump of 
coal is broken and shipped in a cloth sack to the laboratory. This 
allows the moisture to dry out ; moreover, the lump selected is usually 
free from layers of slate and impurities and of course then represents 
the best coal in the lot, and shows a higher value than can be expected 
to hold throughout the coal delivered. 
The preceding statements show that the purchaser should usually 
have the quality determined on the basis of coal " as received," in 
order to correct any excess or deficiency in the moisture content. 
