I

India rubber.....   15 grams

Chloroform......    2 ounces

Mastic..........     0.5 ounce

Mix the india rubber and chloroform together, and when dissolved, the mastic is added in powder. It is then allowed to stand a week or two before using.

II

The following is recommended as very good for cementing pneumatic tires to bicycle wheels:

Shellac.............. 1 ounce

Gutta percha........ 1 ounce

Sulphur............. 45 grains

Red lead............ 45 grains

Melt together the shellac and gutta percha, then add, with constant stirring, the sulphur and red lead. Use while hot.

III

Raw gutta percha.. 18 ounces Carbon bisulphide. 72 ounces Eau de Cologne.. .. 2 and 2/3 ounces

This cement is the subject of an English patent and is recommended for patching cycle and motor tires, insulating electric wires, etc.

IV

A good thick shellac varnish with which a small amount of castor oil has been mixed will be found a very excellent bicycle rim cement. The formula recommended by Edel is as follows:

Shellac............. 1 pound

Alcohol............. 1 pint

Mix and dissolve, then add:

Castor oil........... 0.5 ounce

The castor oil prevents the cement from becoming hard and brittle.

A cement used to fasten bicycle tires may be made by melting together at a gentle heat equal parts of gutta percha and asphalt. Apply hot. Sometimes a small quantity each of sulphur and red lead is added (about 1 part of each to 20 parts of cement).