METHODS EMPLOYED BY VARIOUS MANUFACTURERS OF PAVING BRICK.
Mr. Beattie says : " The brick that we are making in Atchi son, Kansas, is made out of a blue-colored shale that is very hard. We have to use dynamite to blast it. The manner in which we became engaged in that industry I can say was by the Galesburg people, four or five years ago, sending some brick out to Atchison to pave a street. Some of us who had seen the brick became interested in the industry, and took our clays and had them tested, which tests proving satisfactory, we entered into the manufacture of brick. But to continue, as to the manner in which we are making the brick, we use a dry pan, and have a pug-mill and stiff-clay machine.
" So far as my experience goes, the best paving brick I have seen is made by the stiff-clay process. I am not interested in any machines or anything of that kind ; I do not care the snap of my finger for any of them ; but close to where I live there was an effort made to try to make street paving brick by the dry clay process that was a dismal failure ; out of the same mate rial good brick are now made by the stiff-clay method of man ufacture. There may be clays that will make brick by the dry method, and which will do for paving, but for my part I have not seen them yet.
" I would not make the corners of paving brick entirely square, but a very little round at the edge, not so much as most men making brick give it. Where there is too much of a round there is a chance for the wheels of passing vehicles to grind continually on the edges of the brick." Mr. A. 0. Jones, of Zanesville, 0., says : " As to my ideal mode of making the best paving brick I shall refrain from the attempt to mention, but among the methods of manufacture in use in Ohio is that employed in preparing the clay for the manufacturing of sewer pipes. After the clot or glut brick is formed it is then re-pressed, for unquestionably this densifies the body. Re-pressing takes a little more fuel for burning, but it adds greatly to the lasting qualities of the brick. It also gives it a finished look. Good workmanship, and then add to this perfect burning, for this is of the most vital importance, and the result is a good paver."
The Grape Creek Clay Company, of Grape Creek, Ill., uses a shale clay which, when freshly mined, resembles rock. It is first subjected to heavy crushers, put through enormous rollers, ground dry, and elevated to a revolving pan, when two massive rollers running in opposite directions grind the shale to an im palpable powder, and subject it to a sifting process. It is again ground in a gang mill, made into the shape desired. (They make three sizes of blocks-4x4x 12 inches, 4x5x 12 inches, 4x6x12 inches.) The blocks, after being molded, are partially dried, then subjected to an intense pressure, then placed on racks to dry. In burning, the heat is raised gradually and cooled off slowly, by which means the material becomes thor oughly annealed, and the result is a brick tougher than granite.
Messrs. Stewart & Collins, of Hastings, Neb., take a rough clay from the bank and run it through a disintegrator and pug mill, which reduces it to dust, and pug it to a stiff mud, issuing it through the die of a stiff-clay brick machine, which automat ically delivers the brick upon the pallet hard, smooth and straight cut, at the rate of from 35,000 to 40,00o per day of ten hours.
Their clay bank stands thirty feet deep, and is above the track where it is loaded, being a solid mass consisting of an equal mixture of iron, shale and fire-clay. The brick made is of standard size, and when burned weighs six pounds. They use the portable hack, the track system exclusively. The clay will dry in sun or wind. They have had no cracked brick whatever, and use a common up-draft kiln, with coal for fuel, set thirty-four long and thirty-eight high. They burn from ten to twelve days, and use considerable clay on kilns, as the heat shows on top. They fire from both heads at all times, with partitions in centre of each arch, and have no trouble to keep a uniform heat. The firm are satisfied that there are more eco nomical ways of burning, and will introduce them in their plant.