part 7

. Pitch 1 part Shellac 1 part Rubber substitute 1 part

These are used by melting over a burner.

VI. Rosin, Shellac, and Wax.—A strong cement, used as a stone cement, is:

1. Rosin 8 parts Wax 1 part Turpentine 1 part

It has little or no body, and is used in thin layers.

For nitric and hydrochloric acid vapors:

2. Rosin 1 part Sulphur 1 part Fire clay 2 parts

Sulphur gives great hardness and permanency to rosin lutes, but this composition is somewhat brittle.

Good waterproof lutes of this class are:

3. Rosin 1 part Wax 1 part Powdered stone 2 parts

4. Shellac 5 parts Wax 1 part Turpentine 1 part Chalk, etc. 8 to 10 parts

For a soft air-tight paste for ground-glass surfaces:

5. Wax 1 part Vaseline 1