Tin e 
389 
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 ; re- 
move the mixture from the lire, and before it grows cold, 
add five ounces of mercury, and stir the whole well to- 
gether ; then put the fluid amalgam into a clean glassy 
and it is fit for use. 
When this amalgam is used for foiling or silvering, let 
it first be strained through a linen rag ; then gently pour 
some ounces thereof 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 ; the 
globe should then be dexterously inclined every way, 
though very slowly, in order to fasten the silvering ; 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 
superfluous amalgam may then be poured out, and the 
outside of the globe cleared. 
To Silver the Convex side of Meniscus Glasses for 
Mirrors . 
Take an earthen plate, on which pour some prepared 
plaster of Paris, mixed with water, of a proper consis- 
tence ; then immediately, before it grows too stiff! lay the 
meniscus with its convex side downward, in the middle 
of the plate, and press it until it lies quite close to the 
plaster ; in which situation let it remain until the plaster 
becomes quite dry ; after which, work a groove with 
your finger, round the outside of the meniscus, in order 
to let the superfluous mercury rest upon it : then cut the 
tinfoil to a proper size, and press it with the meniscus into 
