no Mr. Hatchett’s Experiments on the various Alloys > 
equal parts of silver and copper, the expansion amounted to 
,67 ; which is the more remarkable, as, in the subsequent article, 
copper being employed singly, produced only an expansion of 
, 66 . It appears, therefore, that the compound alloy of silver and 
copper, being added in the proportion of T x - to gold, causes a 
degree of expansion superior to that produced by copper, although 
it might be previously imagined, that the silver would have 
checked or diminished the expansive property of the copper. 
JL- of iron appears to have caused an expansion rather infe- 
rior to that of copper ; but an alloy composed of equal parts of 
iron and copper, produced an expansion less than the former. 
This effect seems also to be peculiar to this compound alloy ; for, 
according to the effects which copper was found singly to pro- 
duce upon gold, the compound alloy of iron and copper ought 
to have produced an expansion superior to that caused by iron 
alone. 
A considerable contraction was caused when ~ of tin was 
added to gold ; but, as an attempt had been made to pass the 
mass between rollers, before the specific gravity was taken, the 
contraction must not be estimated at so much as ,53. 
When gold was alloyed with equal parts of tin and copper, 
the contraction was found to be only ,02 ; but, in the next case, 
when the copper amounted to 30 grains, and the tin only to 8, - 
an expansion took place, equal to ,14. 
of lead produced an expansion equal to ,14; but, from 
the similarity of all the other effects of lead to those of bismuth, 
I am inclined to believe that lead, in some proportion greater 
than y-, would produce contraction. In all the instances, how- 
ever, stated in the Table, expansion was observed; and, when 
lead was in the proportion of 4 grains to 34 of copper, or of 
