210,069,604.  Now, if we say that coke contains in round numbers 90 per cent. carbon, then we will have 62.97 lb. of coke, equal in heat units to 1,000 cubic feet of natural gas.  Then, if a ton of coke, or 2,000 lb., cost 10s., 62.97 lb. will cost 4d., or 1,000 cubic feet of gas is worth 4d. for its heating power.  We will now compare the heating power of this gas with bituminous coal, taking as a basis a coal slightly above the general average of the Pittsburg coal, viz.: 

Per cent. 
Carbon................................... 82.75
Hydrogen.................................  5.31
Nitrogen.................................  1.04
Oxygen...................................  4.64
Ash......................................  5.31
Sulphur..................................  0.95

“We find that 38 lb. of this coal contains 146,903,820 heat units.  The 64.4 lb. of this coal contains 210,069,640 heat units, or 54.4 lb. of coal is equal in its heating power to 1,000 cubic feet of natural gas.  If our coal cost us 5s. per ton of 2,000 lb., then 54.4 lb. costs 1.632d., and 1,000 cubic feet of gas is worth for its heat units 1.632d.  As the price of coal increases or decreases, the value of the gas will naturally vary in like proportions.  Thus, with the price of coal at 10s. per ton the gas will be worth 3.264d. per 1,000 cubic feet.  If 54.4 lb. of coal is equal to 1,000 cubic feet of gas, then one ton, or 2,000 lb., is equal to 36,764 cubic feet, or 2,240 lb. of coal is equal to 40,768 cubic feet of natural gas.  If we compare this gas with anthracite coal, we find that 1,000 cubic feet of gas is equal to 58.4 lb. of this coal, and 2,000 lb. of coal is equal to 34,246 cubic feet of natural gas.  Then, if this coal cost 26s. per ton, 1,000 cubic feet of natural gas is worth 91/2d. for its heating power.  In collecting samples of this gas I have noticed some very interesting deposits from the wells.  Thus, in one well the pipe was nearly filled up with a soft grayish-white material, which proved on testing to be chloride of calcium.  In another well, soon after the gas vein had been struck, crystals of carbonate of ammonia were thrown out, and upon testing the gas I found a considerable amount of that alkali, and with this well no chloride of calcium was observed until about two months after the gas had been struck.  In these calculations of the heating power of gas and coal no account is of course taken of the loss of heat by radiation, etc.  My object has been to compare these two fuels merely as regards their actual value in heat units.”

Bearing in mind that it is never wise to prophesy unless you know, I hesitate to speak of the future; but considering the experience we have had in regard to the productiveness of the oil territory, which is now yielding 70,000 barrels of petroleum per day, and which has continued to increase year after year for twenty years, I see no reason to doubt the opinion of experts that the territory which has already been proved to yield gas will suffice for at least the present generation in and about Pittsburg.