Natural gas is applicable to all manner of kilns now used. It has been most successfully applied to the up-draft pattern, with or without furnaces. Those without furnaces are probably to be preferred on account of the tendency of the gas to rise to the roof of the furnace and follow it and the inner wall to the brick before it is thoroughly consumed. The Wittmer Co., of Pittsburgh, uses both patterns. The kilns have 20 arches each, with brick to the head and 39 brick wide, holding in the neighborhood of 375,000.
The old kilns in which the slack was used have 3-foot fur naces, whilst the new kilns simply have openings 9 by 24 inches in the 20-inch wall. The results are about equal, the brick being hard to the walls, and to the top, except one course, and free from whitewash or fire-marks, but in those having furnaces the overhangers near the wall are slightly dis colored, while in those without furnace only a half dozen brick near the bottom will be slightly bluish. Gas is successfully used in down-draft kilns, especially for burning tile and terra cotta ware. In these the brick or ware are uniformly burned, but there seems to be a slight tendency to over-color. I do not know if natural gas has been applied to continuous kilns, but feel confident that it would succeed in them. However, they will scarcely come into general use where this cheap fuel is employed, because of the ease with which it is applied and handled in ordinary kilns. With regard to the cost of burning with gas, it varies according to the situation of the yard. If the owner should be fortunate enough to possess a gas well, he would be at only the actual cost for drilling and fitting. Should the yard be situated on a line that is anxious for cus tom, or where there are competing lines, the gas may be had very reasonably under such circumstances. Even under these unfavorable circumstances the brick manufacturer is a gainer, as he saves the cost of labor in hauling, handling, stok ing, and moving the refuse of other fuels, and has a superior quality of brick with less waste. One person can handle all the kilns in a yard by firing hard during the day and easing up at night. The salary paid to gas-burners is considerably above that paid to others, but it is a small item compared to the ag gregate wages paid to the army of men whose services are dis pensed with. A great amount of space that was required for stacking and storing coal is also free to be utilized for other purposes, and a yard can work the year round, without annoy ing the neighborhood or injuring property.
Mr. J. R. Boice was one of the first to use natural gas on its introduction in Toledo, Ohio, and its results have proven satis factory with kilns holding even as many as i,000,000 brick each, the cost of burning being about forty per cent. less than with coal, and the quality and color equally as good as with either wood or coal. Mr. G. B. Smith, of Haverstraw, N. Y., in speaking of the use of gas made at the kilns by his firm as a fuel for burning brick, said : "The cost of burning brick in Haverstraw with soft coal at about $2.50 per ton averages from 85 to 95 cents per thousand for the fuel.
" The idea of burning brick with gas was new to us. We have had but very little trouble in applying it, and our burners have acquainted themselves with it very easily. We are now burning our brick at a cost of some 5o or 65 per cent. less than with wood, and the saving of labor is still greater than that.
" It costs between 3o and 4o cents a thousand to burn brick with gas. We burn a very wide kiln, set 49-50 wide.
" We burn the open-hearth kiln, manufacturing the gas at the mouth of our arch. A pipe runs under the kiln, supplying the liquid carbon, and the steam is supplied from our steam boil ers, and the gas is generated at the mouth of each kiln and burnt green. We actually get the same gas they manufacture for town service—hydrocarbon gas. We get the gas with steam. We can carbonize it with any liquid carbon. We are using a residuum which we get from the refineries in Ohio—a crude oil, after the laminated oil and naphthas are taken out of it. We want carbon only in a liquid. Any substance that con tains a larger per cent. of carbon is the article we want. Tar answers the same purpose where it can be got cheaply.
" The gas requires to be carbonized, because we cannot burn hydrogen without carbonizing it ; if hydrogen could be burned alone in the kiln, it would be the cheapest fuel. Of course, we get it in steam, decomposed by the heat of the furnace, super heated by steam. Our steam is made into hydrogen where it enters the mouth of the kiln. By carbonizing it we get our combustion from a natural draft supply of oxygen, but hydrogen alone with natural draft would not give us combustion in an open furnace.
"The cost of wood averages from $5 to $5.50 per cord at Haverstraw, N. Y., and the saving in cost of fuel, using gas in stead of wood, is from 5o to 65 per cent. In many portions of the country the cost of wood ranges only from about $1.35 to $2 per cord, and in such instances wood is the cheaper fuel. In the cost of burning by gas, as stated above, we estimated the cost of wood in opening the draft, but not the cost of labor, which is a separate item. The size of the brick produced by us is 8 inches long, wide, thick.
" It is difficult to say whether or not this process with wood at $3 a cord and best Indiana or Ohio coal at $3 a ton would be a cheaper process of burning brick, taking all things into consideration, labor and everything.
"There is the question of clays used in different localities. The quantity of wood required to burn some clays is much greater than others. It would depend upon the cost of oil and the cost of transportation. In the State of Ohio oil can be ob tained for about one-half of what it costs on the Hudson river. With our clay and conditions I think the cost is less with oil at present prices than with wood at prices named. We have used very little coal there. The price of crude oil at Haverstraw is about $1 a barrel.
"Two burners at a cost of $160 are required to an arch. The burners are used for two-and-a-half to three days on a kiln, so that the burners would do work in a week's time double that of the old process."