106 CLASSIFICATION OF THE PUBLIC LANDS. 



nous coal, a bituminous, a cannel, or an anthracite coal. It may also 

 be possible to estimate rather closely whether or not a coal contains 

 a large amount of ash. Where small mines or prospects have been 

 opened it may be possible, by studying the coal on the dump, to 

 determine whether the coal can be shipped or stocked, or the extent 

 to which it tends to crumble under the action of the atmosphere. 



The final tests, however, are the chemical test, consisting of an 

 analysis of the coal, which shows fully its percentage of the various 

 heat-giving elements and of the ash and other elements that do not 

 yield heat but detract from its value, and the test of its heat-giving 

 value in the calorimeter. Experience has shown that coal of certain 

 kinds — especially low-grade coal — changes in chemical composition 

 very rapidly when exposed to the weather, so that in getting samples 

 for analysis it has been found necessary, in order that the samples 

 may be fairly compared and may form the basis of a uniform system 

 of classification and valuation, that they be taken with great care 

 in a uniform manner and that the treatment of each sample from 

 the time it is taken until it is analyzed shall follow certain standards. 

 To this end certain regulations have been prepared in regard to the 

 method of obtaining coal samples for analysis and are consistently 

 enforced. These regulations in brief are as follows : 



1. Select a fresh face of unweathered coal at the point where the sample is 

 to be obtained and clean it of all powder stains and other impurities. 



2. Spread, a piece of oilcloth or rubber cloth on the floor so as to catch the 

 particles of coal as they are cut and to keep out impurities and excessive mois- 

 ture where the floor is wet. Such a cloth should be about IJ by 2 yards in size 

 and should be so spread as to catch all the material composing the sample. 



3. Cut a channel perpendicularly across the face of the coal bed from roof to 

 floor, with the exceptions noted in paragraph 4, of such size as to yield at least 

 6 pounds of coal per foot of thickness of coal bed ; that is, 6 pounds for a bed I 

 foot thick, 12 pounds for a bed 2 feet thick, 24 pounds for a bed 4 feet thick, etc. 



4. All material encountered in such a cut should be included in the sample, 

 except partings or binders more than three-eighths inch in thickness and lenses 

 or concretions of " sulphur " or other impurities greater than 2 inches in 

 maximum diameter and one-half Inch in thickness. 



5. If the sample is wet, it should be taken out of the mine and dried until 

 all sensible moisture has been driven off. 



6. If the coal is not visibly moist, it should be pulverized and quartered down 

 inside the mine to avoid changes in moisture, which take place rapidly when 

 fine coal is exposed to different atmospheric conditions. The coal should be pul- 

 verized until it will pass through a sieve with one-half inch mesh, and then, after 

 thorough mixing, it should be divided into quarters and opposite quarters re- 

 jected. The operation of mixing and quartering should be repeated until a 

 sample of the desired size is obtained. When the work has been properly done 

 a quart sample is suflicient to send for chemical analysis. This sample should 

 be sealed in either a glass jar or a screw-top can with adhesive tape over the 

 joint and sent to the chemical laboratory for analysis. 



