SILVERING. 279 



if you be not exceedingly careful, your labour will 

 be lost. 



Another method, is to slide the glass over the 

 foil, without the assistance of paper. 



To Silver Glass Globes. 



Take half an ounce of clean lead, and melt it 

 with an equal weight of pure tin; then immediately 

 add half an ounce of bismuth, and carefully skim 

 off the dross ; remove the mixture from the fire, 

 and, before it grows cold, add five ounces of mer- 

 cury, and stir the whole well together ; then put 

 the fluid amalgam into a clean glass,' and it is fit 

 for use. 



When this amalgam is used for foiling or silver- 

 ing, let it first be strained through a linen rag ; 

 then gently pour some ounces of it into the 

 globe intended to be foiled : the mixture should be 

 poured into the globe, by means of a glass or paper- 

 funnel, reaching almost to the bottom of the globe, 

 to prevent its splashing to the sides j the globe 

 should then be dexterously inclined every way, 

 though very slowly, in order to fasten the silver- 

 ing. When this is once done, let the globe rest 

 some hours ; repeat the operation, till at length the 

 fluid mass is spread even, and fixed over the whole 

 internal surface, as it may be known to be, by 

 viewing the globe against the light ; the super- 

 fluous amalgam may then be poured out, and the 

 outside of the globe cleared* 



' -V 



To Silver the Convex Side of Glasses for Mirrors. 



Take an earthen plate, on which pour some pre- 

 pared plaster of Paris, mixed with water, of a 



T 4 



