By radiation and convection..

In the decomposition of 200 pounds of steam (=22.22 pounds hydrogen X62,000 =)

Absorbed by heating from 250°, to 1,250°, 50 pounds steam that will probably escape decomposition 50X1,000 X.475=

Total heat units expended...

Units of heat remaining....

253,000

1,377,640

23,750

1,654,390

875,610

With this quantity of heat will we have sufficient intensity for the decomposition of steam? Experience says yes, but to determine this theoretically, we must first ascertain the composition and the specific heat of the mixture.

With free escape from the producer it is not probable that the gases would take up the temperature of the fuel. Experience has shown that the gases escape at a temperature of 750° to 900°. If the gases shall escape at a temperature of 1,000 ̊, then an equal weight of the fuel would be increased, thus:

221 X .273

=274°,

.220

and this, added to the 1,221°, would give the temperature of 1,495°.

The gas made in the producer would be about as follows:

TABLE X.-COMPOSITION, QUANTITY AND VALUE OF PRO

Then we have the mixture of the three products in the propor

tions given below:

TABLE XI.-COMPOSITION, QUANTITY AND VALue of

Product.

MIXED GAS.

Quantity, feet. Value per 1,000 feet. Total Units.

It thus appears, then, that 1,000 feet of this mixture has but eighty-nine per cent. of the value of water gas, thus :

The heat units per 1,000 feet can only be increased at the expense of reduction in total quantity. The results obtained are not so good as we ought to have. What part of the process has failed to do good work? Let us see.

With 16.8 per cent. of the weight of coal in the coal gas, it gives 28.58 per cent. of the total heat units possible from the coal; with twenty-five per cent. of the weight of coal used in the production of the producer gas, it gives twenty per cent. of the energy of the coal; with twenty-five per cent of the weight of the coal used in the production of the water gas, it gives but 14.92 per cent. of the energy of the coal in heat units. Here, then, it is clearly shown that the fault lies in the low results, obtained from the fuel converted into water gas.

I believe that 25 feet is about all that will, in practice, be obtained from a pound of coke or hard coal, with generators as now constructed, but we ought to get better results. Notwithstanding the fact that the water gas gives us poorer net results than either of the other processes, if we are to increase the calorific value of the mixed gas, it must be done by decreasing the producer and increasing the proportion of the water gas product.

We will note what the result would have been had the ton of coal been differently treated.

Had all the carbon of the surplus coke from the ton of coal been treated in water-gas apparatus, the quantity would then have been 10,500 feet coal gas plus 20,000 feet water gas, or a total of 30,500 feet, with a total calorific value of 14,164,168 units, which would equal but 52.46 per cent. of the energy of

the coal.

In practice, then, the results obtained are about as follows: From a ton of hard coal in water-gas apparatus, we get 40,000 feet and 51.9 per cent. of energy.

From same quantity of hard coal in producer furnace, we get 150,000 feet and 68.8 per cent. of energy.

From ton of gas coal, when all the surplus coke is treated in water gas apparatus, we get 30,500 feet and 52.46 per cent. of energy.

From same quantity of soft coal, with half of surplus coke converted to water gas and half to producer gas, we obtain 59,800 feet of gas and 63.5 per cent.

From a ton of gas coal converting all the surplus coke to producer gas, we will obtain 84,500 feet of gas, and 64.98 per cent. of the energy of the coal. Producer gas alone cannot be used for domestic purposes, nor do I think it would be safe to use so large a per cent. of producer gas as can be made from the surplus coke of a ton of gas coal. It would not easily ignite, and, under certain conditions, might become extinguished without having the supply cut off, and it would therefore be dangerous to use so large a per cent. of it.

Now, had the ton of soft coal been converted directly into water gas, making permanent gas out of the volatile hydro

carbons, we possibly would have obtained as large a per cent. of the value of the coal as would be obtained by first retorting the coal, though this may be questioned; but in passing the volatile hydrocarbons down through incandescent coke in the presence of steam, we would in a large measure, if not entirely, break up the compounds of the olefiant gas series, to which the odor of coal gas is so largely due, and would also form compounds of less calorific intensity; that is, the carbon would be largely taken from the hydrocarbon compounds and converted into carbonic oxide.

To give the mixed product as high value in heat units per 1,000 feet as water gas contains, we must change the proportions somewhat, and use 667 pounds of the coke in water-gas apparatus, and but 333 pounds of the coke in the producer furnace. Then we will have the proportions and values shown in following table:

The flame temperature of the mixed gas will equal about 4,000° F., and in percentages the mixture will contain coal gas 20.35, water gas 32.17, and producer gas 47.48 per cent.

By thus changing the proportions, we reduce the total quantity in feet by 8,200, and total heat units by 490,850, but the mixture has been increased in value from 287,000 to 323,096 units per 1,000 feet, or to a value that is a fraction better than water gas, while the quantity of gas is twenty-nine per cent. more than we have estimated that 2,000 pounds hard coal or coke would produce of water gas alone.

Having now ascertained the quantity of gas that can be produced from a ton of gas coal, and of a quality that we believe will be desirable, it is necessary to know the cost of the same:

costs $2 per net ton, this item of fuel will add 3.88 cents, and if it costs $3 it will add 5.81 cents, and if coal costs $4 per net ton, it will add 7.71 cents, making gas cost per 1,000 feet in holder, 9.78 cents, 11.71 cents and 13.61 cents, respectively.

Do these prices appear very low? They are not only obtainable, but I believe even better results may be had. I may add that the wages item is intended to cover superintendence. Here we may note some features that to my mind are interesting: That is, the cost of various gases per 1,000,000 units of heat of which they are theoretically capable of producing.

In working out these figures, I put wages, repairs and incidentals as given in last table, and the cost of a ton of good gas coal at $3, and a ton of hard coal or coke at same price, and the quantities of production as follows: Coal gas from soft coal, 10,000 feet; water gas from hard coal, 40,000 feet, and producer gas, 150,000 feet.

TABLE XIV.-COST PER 1,000,000 UNITS OF HEAT.

Coal Gas..

Water Gas...

-734,976 units, at 27.5 cents = 37.42 cents.

Thus will it be seen that after all coal gas costs but 3.26 per

cent. more per unit of heat than the mixture that we have worked