Composition of cement used for the adjustment of the pieces of glass which touch each other.
| 12 | parts | white lead. |
| 1 | do. | minium or red lead. |
| 5 | do. | boiled lintseed oil. |
The whole is pounded on an iron table by means of a flat mullet, like that used by painters ([fig. 112]), whose grinding surface is a b, and c the knob for the hand. This cement is applied liquid so as to offer no resistance to the close union of the pieces, which it is intended to unite.
Fig. 112.
Cement for filling up voids, and fixing the rings in the frames.
| 12 | parts | white lead. |
| 3 | do. | whiting. |
| 1 | do. | minium. |
| 4 | do. | boiled lintseed oil. |
This last composition differs from the former only in the introduction of whiting, which, while like minium it has a desiccative property, gives more body to the cement and prevents the formation of cracks. The oil is also decreased in quantity, as the cement must be used in a more compact state. The trituration of this cement is performed by means of a cylindric iron roller a b, with a centre-spoke c d for the hand ([fig. 113]).
Fig. 113.
