126 Mr. Hatchett’s Experiments on the various Alloys , 
Quality. 
Specific gravity 
before friction. 
Specific gravity 
after friction. 
1 . Gold of 23 car. 3^ grs. fine - 
1 9,277 
19,171 
2. Gold alloyed with silver 
18,092 
18,055 
3. Gold alloyed with silver and 
copper - 
18,184 
l8,l82 
4. Gold alloyed with copper 
18,053 
18,014 
5. Gold alloyed with copper and 
iron - - 
17,151 
17,095 
6 . Gold alloyed with copper and 
tin 
17,607 
17,581 
7. Gold and copper, in equal parts 
12,142 
12,139 
The proportion of gold in the foregoing pieces exceeded, in 
general, the standard quantity ; but that circumstance did not 
interfere with the principal object of these experiments, which 
will also be corroborated by the result of the subsequent ex- 
periment. 
Experiment n. 
Twelve pieces of fine copper, similar in size to those of gold 
which were employed in the former experiment, were weighed 
hydrostatically, altogether, and were afterwards placed in the 
machine, so that six were made to rub against six. After 22200 
revolutions, they were taken out, and their specific gravity was 
again accurately examined. 
A very apparent diminution was found to be the result, for 
the specific gravity was, 
Before friction. After friction. 
8,785 8,283. 
Considering, therefore, that this diminution of specific gravity 
was found in each of the foregoing series, as well as in the 
