Utilization of coal waste.

Manufacturer and builder 7, 1876

Coal-tar, which twenty-five years ago was a waste product, which gas companies did not know how to get rid of without producing a public nuisance and complaints, has at the present day, by the aid of the chemist's art, been lifted up from its lowly place, and stands forth as the source of some of the most useful products in the arts — its horrible color and odor have been transmuted into the most beautiful dyes and the most delicious flavors. The offensive refuse has become the queen of the by-products of many manufactures. Instead of being furtively put out of sight, factories have sprung up where the chemist transmutes gas-tar and ammoniacal liquors into a score of various by-products of wholly different natures and the most curious thing is, that many of them are, as if by magic, elevated into materials which appeal to the sense of beauty and delicacy in every form. Among other products of gas-tar as of insufferable smell, is benzole, which, with nitric acid, produces nitrobenzole, also called all of mirbane, a body resembling in aloe bitter almonds. It is largely used for the purpose of perfuming soap. Benzole itself is a body of great solvent powers, and one of the most effective removers of grease stains known whereas the source from which it springs is one of the greatest sellers in existence. Naphtha is a product of this tar — the source of light in many factories removed from gas-works; when treated with turpentine it is transmuted into camphoric, and illuminates our drawing-rooms. Naphtha is also used in dissolving the various gums, resin, India-rubber, gutta-percha, etc., and by its instrumentality a hundred new substances are thereby introduced to the world.

Anilin, the base of the dyes bearing that name, is obtained from the action of nascent hydrogen, on nitrobenzole. It seems almost incredible that delicate tones of color known under that name should issue from so foul a source; but so it is. The arts would indeed be deprived of one of their most beautiful embellishments if this new agent had not been discovered. A brilliant yellow is again produced by the action of nitric acid. Carbolic acid is converted into carbazotic acid; even red dyes, but of a very ephemeral character, are produced from naphthalin. Almost all the colors of the rainbow issue from it; bat the absence of all color, lampblack, is made by burning with slight access of air the least volatile component of gas-tar.

Among the light oils of tar are some which, mixed with the heavy oils, are effective in preserving wood from rotting, and the tar creosote, carbolic acid, which is a most powerful antiseptic, and one which will come largely into use now that the public is becoming more careful of its health. The production of alum and sal ammoniac, although it can not be said to be recovered from the refuse of gas-works, can with truth be said to be produced from the refuse of coal mines — the shale which roofs them in. Formerly this was a waste material which occupied a vast space, like the spelter heaps. It is now utilized by our dyers and color-printers to fix their colors. This product is made by setting fire to the shale, and heating the residuum in iron pens with sulphuric acid, with the addition of the gas liquor, when the result is ammoniacal alum.

"Perhaps," says Mr. Simmonds, "the most interesting of all the products of coal-tar, is solid paraffin — a colorless, crystalline, fatty substance which may be truly termed' condensed coal-gas.' It is found naturally in the coal measures, and other bituminous strata constituting the minerals known as fossil wax, ozokerit, etc. It consists also in solution in many kinds of petroleum, and may be obtained by distilling off the more volatile portions, and exposing the remainder to a low temperature. The greater bulk of paraffin is however obtained from coaltar. The oil produced from paraffin will only burn with the assistance of a wick, and is therefore perfectly safe; when burning, it splits up into olefiant gas, thus producing a brilliant white light."

We could go on giving a number of other by-products which have grown out of the utilization of gas-waste. We may say that chemistry is by far the most fertile agent in turning so-called refuse into manifold new uses. Her magic wand, as we have seen, has only to touch the most noisome substances, and the most ethereal essences, the most heavenly hues, the most delicate flavors and odors, instantly arise as if by magic.