The cost of reclaiming rubber by the acid process is less than by mechanical means, for which reason the former is now much more generally used. But some manufacturers are willing to pay more per pound for mechanically-reclaimed rubber, either (1) because it can be "compounded" more heavily than the acid product, or (2) because of certain inherent disadvantages of the latter. It is the testimony of these manufacturers that the action of sulphuric acid upon whiting (one of the most common adulterants used in rubber shoes) is to turn it into sulphate of lime—an ingredient which is far from advantageous in a rubber compound. Again, any acid which may remain in the reclaimed rubber is liable to rot thin textile fabrics with which it may be combined in manufacture. Finally, rubber recovered by the chemical process, it is claimed, is harder than that obtained by any other; so that it is usual to add, during vulcanization, in order to soften the product, the residuum obtained from petroleum manufactures, or palm or other oils. Unvulcanized rubber clippings also have been used for this purpose. One of the most successful of our rubber factory superintendents, who formerly made the reclaimed rubber used by his factory, has stated that his practice was to subject the material to an alkaline bath after the acid treatment, not only for the better cleaning of the rubber, but to neutralize any acid which might remain. Considering all the points involved, it was his opinion that, when scrap rubber is cheap, the mechanical process is the more economical, while, if it is high priced, the acid process has the advantage. Since this expression of opinion, however, prices of rubber scrap have ranged constantly at higher figures than before, and there is no indication that we shall have again what was known formerly as "cheap" scrap. It is not surprising, therefore, that the volume of mechanical "shoddy" should be placed by the best estimates at not above one-sixth of the total production of reclaimed rubber in the United States. And the acid product, with all its admitted shortcomings, is still superior to any of the so-called rubber substitutes.
Reclaimed rubber is not to be considered as an adulterant, except in the same sense as fillings, like whiting, litharge or barytes, the use of which in rubber compounds often gives to the product desirable qualities that are unobtainable by the use of "pure gum." It lacks some of the qualities of good native rubber, and yet it is rubber, and fills its proper place as acceptably as any raw material of manufacture. Rubber shoes made of new gum entirely would be too elastic, and for that reason would draw the feet, besides being too costly for the ordinary trade. The construction of a rubber shoe, by the way, is well adapted for the use of different compounds for the different parts. Rubber enters into twenty-six pieces of a rubber boot and nine or more pieces of a rubber shoe. Consequently, as many different compounds may be used, if desired, for the output of a single factory for rubber footwear. The highest grades of native rubber may be used for waterproofing the uppers of a fine overshoe, while reclaimed rubber, of a cheap class even, may be good enough for the heel, which requires only to be waterproof and durable, without too much weight, and with no elasticity. Reclaimed rubber goes into many classes of goods of high grade. The result is that such goods have been cheapened legitimately, placing them within the reach of immense numbers of consumers who otherwise would be obliged to do without.
While the extensive use of reclaimed rubber is a matter of common knowledge to all who are familiar with the rubber industry, there are nowhere available any statistics of either the absolute or comparative volume of its consumption, with the single exception of the official returns of imports into Canada. There separate accounts are kept of crude India rubber and of recovered rubber received in each year, and as only a consuming market exists for these commodities in the Dominion, the figures given below may be taken to represent closely the actual consumption by the rubber factories of Ontario and Quebec. It is interesting to note the heavy growth of the percentage of recovered rubber shown in the table, all the figures representing pounds:
| Fiscal Year. | Crude Rubber. | Recovered Rubber. | Total Imports. | |
| 1885-86 | 739,169 | 19,499 | 758,668 | |
| 1886-87 | 785,040 | 46,508 | 831,548 | |
| 1887-88 | 1,225,893 | 88,471 | 1,314,364 | |
| 1888-89 | 1,669,014 | 221,674 | 1,890,688 | |
| 1889-90 | 1,290,766 | 147,377 | 1,438,143 | |
| 1890-91 | 1,602,644 | 8,254 | 1,610,898 | |
| 1891-92 | 2,100,358 | 106,080 | 2,206,438 | |
| 1892-93 | 2,152,855 | 195,281 | 2,348,136 | |
| 1893-94 | 2,077,703 | 529,900 | 2,607,603 | |
| 1894-95 | 1,402,844 | 611,745 | 2,014,589 | |
| 1895-96 | 2,155,576 | 643,169 | 2,798,745 | |
| 1896-97 | 2,014,936 | 1,061,402 | 3,076,338 | |
| Percentage, | 1885-86 | 97.5 | 2.5 | 100 |
| " | 1896-97 | 65.5 | 34.5 | 100 |
If it were possible to examine the books of the several rubber reclaiming plants on this side of the border, including rubber shoe and mechanical goods factories producing their own reclaimed rubber, the percentage of this material used, in comparison with the total rubber consumption, might be found to be as great in the United States as in Canada. The rubber manufacture in the Dominion, in its inception, was practically an offshoot from the industry in this country. Our manufacturers supplied the Canadian demand for rubber goods until, under the stimulus of heavy protective duties, rubber works were established beyond the border, since which time, to quote a leader in the trade in the United States, "the methods of the Dominion rubber industry have mirrored the best practice in our country." Hence it seems not unreasonable to conclude that if the Canadians are using so large a percentage of reclaimed rubber, they are doing no more nor less than the older and larger concerns here. The most trustworthy authorities place the consumption of new rubber in the United States during 1897 at not far from 35,000,000 pounds. Assuming that the rate of consumption of reclaimed rubber was as great as in Canada, we have 18,435,000 pounds more, or a total of 53,433,000 pounds. But there are producers of reclaimed rubber who insist that the amount of this material used in this country equals, pound for pound, the consumption of new rubber.
The use of reclaimed rubber in Europe is increasing gradually, and especially in Great Britain. The American product is sold extensively in that country, and some native reclaiming plants have been started. The most extensive "galosh" factory in Russia, which is said to be the largest in the world, is reclaiming rubber according to American methods. But, as a rule, the Continental rubber manufacturers make more use of "substitutes," a class of materials which has not found favor in America. These rubber substitutes belong chiefly to the class of oxidized oils and may be classed in three divisions: Those obtained (1) by the action of oxygen or air on linseed oil; (2) by acting on rape oil with chloride of sulphur; and (3) by the action of sulphur on rape oil at a high temperature. The first class has little application to the rubber trade, though its use is universal in the linoleum industry. In Europe the chemist holds a more important position in the rubber manufacture than here, one result of which has been cheaper compounds of rubber and another the satisfactory employment of the refractory African rubbers long before they were used extensively in the United States. Hence the cost of raw materials in the rubber industry has been, on the whole, cheaper abroad. The Europeans have had an advantage, too, in respect to cheaper labor, which has offset somewhat our own advantage from the use of reclaimed rubber as a cheap material.
There are numerous grades of reclaimed rubber, due to differences in the quality of stock used, and also to the different degrees of care used in its preparation, according to the requirements of manufacturers. The declared value of reclaimed rubber exported from New York during July, 1897, averaged 12.6 cents per pound, while the value of exports for September averaged only 9.1 cents. The average value for the eight months ending February 28, 1898, was 10.08 cents per pound. The total declared value of such exports for the fiscal year 1896-97 was $119,440, which, at the prices prevailing since, would represent considerably more than 1,000,000 pounds. Some of the material sold at home is known to bring less than any prices quoted above. "Mechanical" stock brings about two cents per pound more than "acid" stock of corresponding grade.
The collection of old rubber has acquired large proportions as an adjunct to the trade in junk or rags. Not long ago the estimated yearly collection of rubber shoes alone amounted to 18,000 tons, and since that time the business in bicycle tire scrap has also become very large. During the past ten years the price of old rubber shoes has ranged between $60 and $120 per ton in carload lots, being at present about $90 per ton. Some 1,500 tons of rubber scrap are imported annually by the reclaiming companies in the United States.
In the Baltic Sea there are more wrecks than in any other place in the world. The average throughout the year is one each day.