MOULDING AND CASTING. 289 



clearing the cavity, as all dust, ashes, or small 

 detached bodies, will necessarily rise to the surface 

 of the quicksilver, and be poured out with it. 

 The mould being thus prepared, it must be heated 

 very hot when used, if the cast is to be made 

 with copper or brass, but a less degree will serve 

 for lead or tin. The metal, being poured into the 

 mould, must be gently struck, and then suffered 

 to rest till it be cold ; at which time it must be 

 carefully taken from the cast, but without force ; 

 for such parts of the matter as appear to adhere 

 more strongly must be softened, by soaking in 

 water till they be entirely loosened, that none of 

 the more delicate parts of the cast may be broken 

 off or bent. 



When talc cannot be obtained, plaster alone 

 may be used ; but it is apt to be calcined by the 

 heat used in burning the animal or vegetable from 

 whence the cast is taken, and to become of too 

 incoherent and friable a texture. Stourbridge, 

 or any other good clay, washed perfectly fine, and 

 mixed with an equal part of fine sand, may be 

 employed. Pounded pumice-stone, and plaster of 

 Paris, in equal quantities, mixed with washed clay 

 in the same proportion, is said to make excellent 

 moulds. 



Method of taking a Cast in Plaster from a 

 Person's Face. 



The person whose likeness is required in plaster 

 must lie on his back, and the hair must be tied 

 up so that none of it covers the face. Into 

 each nostril convey a conical piece of stiff paper 

 open at both ends, to allow of breathing. The 



VOL. II. U 



