CHARACTEE OF COAL. 43 
substance derived from the leaching of the adjacent rocks. A test by 
George Steiger of some of this material from the coal in Horse Canyon. 
Utah, showed it to be a hydrous silicate of aluminum containing a 
small amount of calcium carbonate. 
The moisture content of the coal is shown in the table of analyses on 
pages 44-46. The moisture in the "sample as received," which repre- 
sents the condition of the coal in the mine, ranges from 4.71 to 18.63 
per cent. By air drying in the laboratory these samples lost between 
0.10 and 5.30 per cent of their moisture. On exposure to the weather 
the coal becomes dull and breaks up along the joints into small 
prisms which finally crumble to powder. The rapidity with which 
disintegration occurs is not well known, for little coal is allowed to 
remain about the mines. A considerable amount, however, was 
found at the prospects in Horse Canyon; although this was reported 
to have lain in a heap exposed to the weather tor more than a year, it 
showed little apparent deterioration. 
CHEMICAL COMPOSITION. ' 
The following analyses show the composition of a number of samples 
of coal from the eastern part of the Book Cliffs field. Samples were 
taken from the most important mines and prospects under uniform 
conditions, and represent the freshest available material. The sam- 
ples were collected by cutting a channel across the face of the coal 
from roof to floor, partings more than a quarter of an inch in thickness 
being rejected. The material was gathered on canvas, crushed, mixed, 
and quartered down to about 3 pounds, and sent to the laboratory in 
sealed cans. The analyses were madcat the fuel-testing plant of the 
United States Geological Survey at St. Louis, under uniform con- 
ditions prescribed by X. W. Lord." 
The analysis of each sample is tabulated in two forms, showing the 
composition of the air-dried sample and the sample as received at the 
laboratory. The air-dried analysis shows the percentage of the 
several constituents of the coal after it has been powdered and allowed 
to lose the moisture that evaporates on exposure to the atmosphere 
of the laboratory until a constant weight results, the percentage of 
air-drying loss being shown in the table. The analysis of the sample 
as received shows the percentage of the several constituents of the 
coal, including the total amount of water contained in the sample a>< 
received at the laboratory, and represents the condition of the coal in 
the mine. For general purposes the figures for the air-dried sample 
are best for comparison with other analyses. Proximate analysesof 
« l'rof. Paper U. s. Geol. Survey No. 48, L906 \>. L74e 
