specific Gravity, and comparative Wear of Gold. 109 
Table II. ( continued .) 
Metals. 
Specific 
gravity. 
Weight. 
Bulk before combination, 
in grains of water. 
Bulk after 
combina- 
tion. 
Expansion. 
Contrac- 
tion. 
Specific 
gravity of 
the mass. 
Gold - 
Copper - 
Antimony 
19,172 
8,895 
6,712 
grains. 
442 
34 
4 
z 3’°5 I 
3,82 \ 27,47 
,60 J 
27,94 
>47 
- 
17,169 
Gold - 
Copper - 
Antimony 
19,172 
8,895 
6,712 
442 
37>75 
0,25 
2 3»°5 ] 
4’ 24 \ 27,33 
,04 J 
28,1 1 
>78 
— 
17,07s 
Although the experiments upon which I have formed the 
preceding Table were made with considerable care and atten- 
tion, yet it certainly would not be right to suppose the degrees 
of expansion or contraction to be rigidly and exactly determined 
in every fractional part ; for, besides the almost impossibility of 
totally preventing the escape of some part of the more volatile 
metals, even a variation in the degree of heat during melting, 
as well as in the mode of cooling, must make some difference, 
for which an allowance ought to be made ; but these unavoidable 
inaccuracies, do not prevent the more general and essential effects 
from being ascertained. 
Very little alteration appears to have been produced by alloying 
gold with J- of pure silver;* for the alloyed mass only differed 
from the natural bulk of the two metals by ,10 ; and this ac- 
cords with former observations upon the effects which these 
metals produce on each other. 
But, in the next case, which consisted of gold alloyed with 
* In this and every other case, when the proportion of alloy was estimated, an 
allowance has been made for the deficiency in the quality of the gold, amounting to 
half a carat grain. 
