By HAWTHORNE HILL.

The complaint of high prices of India rubber is as old as the rubber industry, one result of which has been an unceasing effort to discover a practical substitute. Never was the secret of the transmutation of metals sought more persistently by ancient philosophers than the secret of an artificial rubber has been by modern chemists, but, thus far, the one search has been hardly more successful than the other. One discovery has been made, however, by which our rubber supplies have been so far conserved that, for the want of it, we might be obliged now to pay double the current prices for new rubber. This is the reclaiming of rubber from worn-out goods, in a condition fit for use again in almost every class of products of the rubber factory.

Soon after the vulcanization of rubber became fully established, attempts began to be made to "devulcanize" the scrap and cuttings of rubber which accumulated in the factories. So extensive were these accumulations that one company are reported to have built a road with rubber scrap through a swamp adjacent to their factory, while most other manufacturers were unable to find even so profitable a use for their wastes. As time advanced there came to be large stocks, also, of worn-out rubber goods, such as car springs and the like, all of which appealed to a practical mind here and there as being of possible value, since the price of new rubber kept climbing up all the while.

No fewer than nineteen patents were granted in the United States for "improvements in devulcanizing India rubber," or "restoring waste vulcanized rubber," beginning in 1855, or eleven years after the date of Goodyear's patent for the vulcanization process. In that year Francis Baschnagel obtained a patent for restoring vulcanized rubber to a soft, plastic, workable state, by treating it with alcohol absolutus and carbon bisulphuratum, in a closed vessel, without the application of heat. Later he obtained a patent for accomplishing the same result by "boiling waste rubber in water, after it has been reduced to a finely divided state;" and still later, one for treating the waste to the direct action of steam.

Patents were granted in 1858 to Hiram L. Hall, for the treatment of waste rubber by boiling in water; also, by subjecting it to steam; and again, by combining various resinous and other substances with it. The two inventors named assigned their patents to the Beverly Rubber Company, of Beverly, Mass., controlled then by the proprietors of the New York Belting and Packing Company, and their processes became the basis of an important business in rubber clothing.

The low cost of the devulcanized rubber, as compared with new rubber, alone gave them a great advantage over other manufacturers, in addition to which they escaped the payment of a license to work under the Goodyear patents.

Many army blankets, made for the government during the civil war, were waterproofed with Hall's devulcanized rubber, and from that period little new rubber has been used in the manufacture of heavy rubber coats. The other patents in this class do not deserve special mention.

It having been established that rubber is rubber, no matter where found, manufacturers gradually turned their attention beyond the scraps and cuttings which remained after making up their goods. There was beginning to be a good demand for ground-up rubber car springs, wringer rolls, tubing and other rubber goods free from fiber, after it had been so treated as to remove the sulphur contents and restore the gum to a workable condition. But this left out of account rubber footwear, belting, and hose, not to mention the later heavy production of bicycle tires. There were only a few uses to which rubber waste containing fibrous material could be put when ground up and devulcanized without the removal of the fiber. It could be put into a cheap grade of steam packing or mixed in a powdered form with new rubber for the heels of rubber boots and shoes. There was an early patent for a process for "combining fibrous materials with waste vulcanized rubber, rendered soft and plastic." But all the other patents which come within the scope of this article had for their object the separation of fibers from the rubber.

An important advance was marked by the Hayward patent (No. 40,407), granted in 1868, for "boiling waste rags of fibrous material and rubber in an acid or alkali, for the purpose of destroying the tenacity of the fibers of the rags, so that the rubber may be reground." But this process extended only to the weakening of the fibers, and not their complete destruction. A later patent, in the same year, provided for exposing the ground rubber waste to the direct action of flames of gas or inflammable liquids, by which the foreign matters would be consumed and the rubber rendered plastic and cohesive, but it is not on record that this process received any particular application.

The principal activity of invention in the field of reclaiming rubber dates from 1870, since which year 37 patents have been granted for processes more or less distinctive from those which had for their object only the devulcanization of rubber. Prior to that time the use of rubber reclaimed from fibrous wastes had been confined practically to one large factory in Boston and one near New York. One concern, for a while, bought old rubber shoes and sent them to women in the country, whom they paid so much a pound for the rubber stripped off - a very expensive process. There were several claimants for priority in the matter of reclaiming rubber by the processes which finally became standard, and some conflicting interests were brought together under the head of the Chemical Rubber Company. This corporation controlled the leading patents for the "acid" process, licensing various parties to work under them, and bringing suits against concerns who reclaimed rubber without their license. In 1895 the United States courts decided in favor of the defendants, practically rendering the patents invalid, on the ground that the inventions claimed under them had been disclosed by the Hall patents of 1858 and the Hayward patent of 1863.