On the Manufacture of Tin-plate. 349 
copper, if unprotected by some such cover- 
ing. ‘The affinity of tin for copper is far- 
ther exemplified by the process of whitening 
pins, which is effected by boiling the pins 
with granulated tin, in a lie made with alum 
and tartar.* 
A useful alloy is likewise formed by the 
mixture of tin and antimony. ‘This metallic 
compound is very white—extremely hard— 
and will bear a very fine polish. On these 
accounts it is employed in making specula 
for telescopes, and also for the manufacture 
of rolled plates to engrave music upon. 
The next metal which I have mentioned 
as uniting readily with tin—is lead. This me- 
tal will combine with tin in any proportion— 
and in most proportions the lead acquires a 
greater degree of fusibility by its union with 
the tin. ‘It is this alloy which forms plum- 
bers’ solder—but that compound is prepared 
with different proportions of tin, according 
to the purpose for which it is intended. The 
article called tin-foil, used for lining tea cad- 
dies, for coating electrical jars, and for other 
purposes, is also made from a mixture of 
these two metals. 
* An interesting Memoir on the tinning of common 
Pins, (by M. Gadolin) will be found i in the Journal de 
Physique for the year 1789, 
