clay and super-silicate of potash,* ground and mixed in such proportions as upon experiment harmonize with the density of the Glass; and this, when moulded into a bas-relief or bust, (in plaster of Paris moulds,) should be slightly baked, and then suffered gradually to cool; or the cameos may be kept in readiness till required for incrustation, for which purpose they should be carefully reheated to redness in a small Stourbridge clay muffle. A cylindrical flint Glass pocket is then prepared, one end adhering to the hollow iron rod, M, with an opening at the other extremity, into which the hot composition figure is introduced; the end, N, is then collapsed and welded together by pressure, at a red heat, so that the figure is in the centre of the hollow hot Glass pocket or muffle. The workman next applies his mouth at the end of the tube, O, while rewarming the glass at the other extremity; but instead of blowing, he exhausts the air, thus perfecting the collapse, by atmospheric pressure, and causing the Glass and composition figure to be of one homogeneous mass, as P.

Small bas-reliefs and casts of coins or medals are incrusted in a more expeditious manner, and especially upon hollow