specific Gravity , and comparative Wear of Gold. 175 
was extremely unequal; and, towards the conclusion of the 
experiment, they were so coated by the abovementioned crust, 
as no longer to be abraded ; and the horizontal wooden table 
alone experienced the effects of the friction. 
After various trials, it was found necessary to remove the 
leaden weights, = 19825 grains, which had been hitherto always 
employed. So that the pieces in the experiment now to be 
related, were only pressed upon the table by the weight of their 
respective brass frames, == 1604 grains ; and, in addition to 
other precautions in this experiment, the sand was not loosely 
scattered, but was cemented upon the horizontal table by a so- 
lution of isinglass. 
By these means, the following experiment was made with 
success.* 
Experiment 11. 
Table IX. 
Number of revolutions, 880. 
1 i 
Quality. 
Weight be- 
fore friction. 
Weight after 
friction. 
Loss. 
Gold 23 car. qf grs. unstamped 
. Grains. 
286,70 
Grains. 
268,60 
Grains. 
18,10 
Gold 23 car. 3-2- grs. stamped 
288,70 
286,60 
20,10 
Gold made standard by silver, 
unstamped - - - 
271 - 8 0 
254,80 
16,50 
Gold made standard by silver, 
stamped - 
271,40 
253,80 
17,60 
* Two pieces of each of the various kinds of gold, &c. were subjected to this 
experiment. 
