Fig. 649.
Fig. 650.
Fig. 651.
Fig. 652.
There are compounds used for making joints on which the plastic matter, which is subject to much change of volume between the liquid and solid state, is mixed with a neutral substance, like sand, which, combining mechanically with it, replaces from 90 to 95 per cent. of the total mass, and reduces its shrinkage to an inappreciable quantity.
