[ 68 ° 3 
hammer, without at all ftretching j which pure zinc 
does in a confiderable degree. 
4. With Regulus of Antimony. 
Regulus of antimony, the moll difficultly fufible 
of the femi-metals, diffolved, in a ftrong fire, equal 
its weight of platina. The compound looked of a 
much duller colour than the regulus at firfi:; and 
broke of a clofe and uniform, though uneven, fur- 
face. It proved confiderably harder to the file, but 
not remarkably more or lefs brittle. 
On increafing the quantity of the regulus, the 
compound proved brighter, and of a leafy texture, 
little different from that of the pure regulus. 
Platina mixed with Compound Metals. 
1. With Brafs. 
1 . Equal parts of platina and brafs, covered with 
borax, and urged with a quick fire in a blaft furnace, 
melted perfedtly together, and fcarce fuffered any 
lofs. The mixt was of a greyiffi white colour, filed 
hard like bell-metal, broke from a blow of the ham- 
mer, without ftretching or receiving any impreffion, 
and flew afunder on endeavouring to cut it with a 
chiffel. Internally, it appeared of an uniform fine 
grain, a clofe texture, and a darker colour than on 
the outfide. It bore a very fine polifh, and did not 
tarniffi on being expofed to the air in a dry room for 
many months. 
2. One part of platina and two of brafs, melted 
in a flow fire, loft about one-thirty-fixth. The in- 
got was of a duller colour than the foregoing, with 
a faint 
