Cement for Vulcanized India Rubber.—Stockholm pitch, 3 parts; American resin, 3 parts; unmixed india rubber, 6 parts; oil of turpentine, 12 parts. Heat and mix very thoroughly. More oil of turpentine may be added as required.

Gutta-Percha Cement for Leather.—Soak gutta-percha in boiling water. Soften in benzole after cutting up for a day. Heat on a water bath until the greater part of the benzole is expelled. When cool it will solidify. Use by heating.

Cement for Rubber Shoes.—

(1)Chloroform280parts.
India rubber (masticated) 10”
(2)India rubber 10”
Resin 4”
Venice turpentine 2”
Oil of turpentine 40”

For first solution dissolve by mastication. For second, melt the finely divided gum with the resin, add the Venice turpentine and finally the oil of turpentine. Use heat if necessary. Mix both solutions finally. To apply, saturate a piece of linen with the cement and apply to the spot previously coated with the cement. As it dries apply a little more as required. A finishing varnish is given in the last chapter. Parkes’ cold curing process may be applied as described in chapter XI.

Chatterton’s Compound for uniting sheets of gutta-percha in cable cores and for general work with gutta-percha coated wires.—Stockholm tar, 1 part; resin, 1 part; gutta-percha, 2 parts.

Waterproofing for Wooden Battery Cells.—Resin, 4 parts; gutta-percha, 1 part; boiled oil, a little.

Another Formula.—Burgundy pitch, 150 parts; old gutta-percha in fine shreds, 25 parts; ground pumice stone, 75 parts. Melt the gutta-percha and mix with the pumice stone and then add the pitch, melting all together. Apply melted and smooth off with a hot iron.

Cement for Celluloid.—Shellac, 1 part is dissolved in spirits of camphor 1 part, with 3 to 4 parts strong alcohol. It is applied warm and the parts united must not be disturbed until the cement is hard.