The following formulas have been recommended:

I

Caoutchouc, 5 parts; chloroform, 3 parts. Dissolve and add gum mastic (powder) 1 part.

II

Gutta percha, 16 parts; india rubber, 4 parts; pitch, 2 parts; shellac, 1 part; linseed oil, 2 parts. Reduce the solids to small pieces, melt together with the oil and mix well.

III

The following cement for mending rubber shoes and tires will answer similar purposes:

Caoutchouc in shavings. . 10 Parts

Rosin................ 4 by

Gum turpentine........ 40 weight.

Oil turpentine, enough. Melt together first the caoutchouc and rosin, then add the gum turpentine, and when all is liquefied, add enough of oil of turpentine to preserve it liquid. A second solution is prepared by dissolving together:

Caoutchouc.......... 10 parts by

Chloroform.......... 280 weight.

For use these two solutions are mixed. Wash the hole in the rubber shoe over with the cement, then a piece of linen dipped in it is placed over it; as soon as the linen adheres to the sole, the cement is then applied as thickly as required.