18 
BALL AND SIMPSON: COALFIELDS OF INDIA. 
was speedily constructed and mines were opened at Tikak and in 
the Namdang and Ledo valleys. In 1884 the output of the colliery 
was 16,493 tons and since that time the production has steadily 
increased, the output during the last five years averaging 292,000 
tons per year. In 1910 the output was 297,094 tons. Briquetting 
plant and machinery for washing the coal previous to coking has 
been in operation for some years past. 
The coal is a brownish-black to black, hard, bright substance 
with an irregular cleavage. It does not soil the fingers when touch- 
ed. It produces a hard, porous, somewhat dull-looking, but excel- 
lent coke, and is a valuable gas coal, yielding 10,900 cubic feet of 
gas per ton, the gas having an illuminating power of 17' 2 sperm 
candles. The average composition ^ of 10 samples of the coal is : — 
Carbon 75-90 
Hydrogen 5-18 
Oxygen and Nitrogen ...... 12-42 
Sulphur 2-32 
Ash 2-03 
Water 2-15 
The average theoretical calorific value of the same samples was 
7,447 calories, which compares very favourably with the value of 
6,520 calories calculated for 31 Eaniganj coals. The most serious 
defects of the fuel are the large amount of sulphur which it con- 
tains either as nodules or disseminations of pyrites, and the state 
of '"small "in which it is placed on the market. In the first trials 
these defects were considered formidable but by the use of specially 
designed firebars and grates they have been overcome, and Assam 
coal has now a reputation as the finest coal in India, and the 
equal of many English fuels. 
Jaipur.'^ — The coal-bearing strata of this field extend as a 
nan'ow fringe along the western edge of the Tipam hills. The 
field is divided naturally into three portions by the rivers Dihing and 
Disang, on the bank of the former of which and within a mile of 
the coal outcrops, is situated the town of Jaipur, which gives its 
name to the coalfield. The length of the outcrops known is about 
24 miles. The dip of the rocks is to the east or towards the axis 
of the range, at angles of from 30° to 80°. Only the uppermost 
1 Jtec. G.S.I., Vol. XV, ]>. 61. 
« Simpson, R. R.: Bee, Geol. Sur. Intl., XXXIV, pp. 200-215 (1906). 
