Austin G. Day tried hundreds of experiments and took out many patents for rubber substitutes. He was in a measure successful, his "Kerite" compound proving of great value and being a result of his seeking for something that would wholly supplant rubber. As far back as 1866 he made public the results of some of his work, giving as formulas for rubber substitutes the following compounds:

I

Linseed oil.........     2 pounds

Cottonseed oil......     1 pound

Petroleum.........     2 pounds

Raw turpentine ....     2 pounds

Sulphur...........     2 pounds

Boil 2 hours.

II

Linseed oil........   2 pounds

Cottonseed oil..... .     1 pound

Petroleum.........     1 pound

Raw turpentine.....     2 pounds

Castor oil..........     1 pound

Sulphur...........     2 pounds

Boil 0.5 hour.

III

Linseed oil.........     2    pounds

Cottonseed oil......     1    pound

Petroleum. . .......     1    pound

Raw turpentine .... 0.5  pound

Liquid coal tar. ....     3    pounds

Peanut oil.........     1    pound

Spirits turpentine...     1    pound

Sulphur...........     4    pounds

Boil 35 minutes.

IV

Linseed oil.........     2 pounds

Cottonseed oil......     1 pound

Petroleum.........     2 pounds

Raw turpentine ....       0.5 pound

Liquid coal tar.....     2 pounds

Spirits turpentine...     1 pound

Rubber...........          pound

Sulphur...........     2 pounds

Boil 1 hour.

In 1871 Mr. Day had brought his experimenting down to the following formula:

V

Cottonseed oil...... 14 pounds

Linseed oil......... 14 pounds

Asphaltum........ 8 pounds

Coal tar........... 8 pounds

Sulphur........... 10 pounds

Camphor.......... 0.5 pound

In this the tar and asphaltum were first mixed with the cottonseed oil, after which was added the linseed oil and camphor, and, last of all, the sulphur, when the temperature was about 270° F. A substitute designed to be used in rubber compounding in place, say, of reclaimed rubber, was made as follows:

VI

Cottonseed oil...... 27 pounds

Coal tar........... 30 pounds

Earthy matter...... 5 pounds

To be mixed and heated to 300° P., and then strained and cooled to 200° F. Then were added 27 pounds linseed oil, the heat raised to 220° F., and 15 to 18 pounds of sulphur added, the heat being continually raised until the mass was sulphurized. When the heat reached 240° F., 1 to 1.5 ounces of nitric acid were added, and at 270° to 280° F., from 1 to 3 ounces camphor were added to help the sulphurization. The resultant compound was used on the following basis:

VII

Para rubber. ...... 20 pounds

Litharge........1 5 pounds

Sulphur........... 1 pound

Above com-

pound......20 to 40 pounds

Mr. Day did not insist on the compound quoted, but advised that the proportions be varied as widely as the exigencies of the case might demand. Whiting, barytes, infusorial earth, white lead, blacks, in fact almost any of the oxides, carbonates, or earthy materials commonly used in compounding, were used in connection with his substitute, as also were any grades of crude rubber. Among other ingredients that he found of use in making his substitutes were vegetable and animal waxes, together with ozokerite and paraffine. These were only used in small quantities, and always in connection with the linseed and cottonseed oils, and generally asphaltum or coal tar. One of his compounds also called for a quantity of golden sulphuret of antimony, presumably to assist in the sulphurization, and a small amount of tannic acid.