| 1. | Refined lake asphalt. | |
|---|---|---|
| 2. | Asphalt | 4 parts |
| Paraffine | 1 part | |
| 3. | Asphalt | 10 parts |
| Paraffine | 2 parts | |
| Boiled oil | 1 part | |
Any of these may be thinned with hot benzol or toluol. Toluol is less volatile than benzol and about as cheap, if not cheaper, the straw-colored grades being about 24 cents per gallon.
Examples of so-called “stone cement” are:
| 4. | Pitch | 8 parts |
|---|---|---|
| Rosin | 6 parts | |
| Wax | 1 part | |
| Plaster | 1/4 to 1/2 part | |
| 5. | Pitch | 8 parts |
| Rosin | 7 parts | |
| Sulphur | 2 parts | |
| Stone powder | 1 part |
These compositions are used to unite slate slabs and stoneware for domestic, engineering, and chemical purposes. Various rosin and pitch mixtures are used for these purposes, and the proportions of these two ingredients are determined by the consistency desired. Sulphur and stone powder are added to prevent the formation of cracks, sulphur acting chemically and stone powder mechanically. {34} Where the lute would come in contact with acid or vapors of the same, limestone should not be the powder used, otherwise it is about the best. Wax is a useful ingredient to keep the composition from getting brittle with age.
A class of lutes under this general grouping that are much used are so-called “marine glues” (q. v.). They must be tough and elastic. When used for calking on a vessel they must expand and contract with the temperature and not crack or come loose.
Formulas:
| 6. | Pitch | 3 parts |
|---|---|---|
| Shellac | 2 parts | |
| Pure crude rubber | 1 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: