specific Gravity, and comparative Wear of Gold. 157 
Experiment iv. 
This resembled the former experiment, excepting that stamped 
pieces were employed. 
Table IV. 
Number of revolutions, 83520. 
Quality. 
Weight be- 
fore friction. 
Weight after 
friction. 
Loss. 
1. Gold 23 car. 3^ grs. - 
Grains. 
142,10 
Grains. 
142,50* 
Grains. 
2. Gold 23 car. 3^ grs. 
142,20 
140,5° 
1,70 
3 . Gold with silver 
154.4° 
153,60 
0,80 
4. Gold with silver - 
1 59 
158,9° 
0.10 
5. Gold with silver and copper 
■ 137.6° 
137,4° 
0,20 
6. Gold with silver and copper 
137.7° 
136,80 
0,90 
7. Gold with copper 
135.5° 
135,3° 
0,20 
8. Gold with copper - 
135.5° 
135,4° 
0,10 
9. Gold with iron and copper 
137,2° 
134 
3,20 
10. Gold with iron and copper 
i35,8o 
133,8° 
2,0 
11. Standard silver 
85,80 
84.50 
1,3° 
12. Standard silver - 
86,90 
84,50 
1,7° 
13. Copper - - - 
82,40 
38 
44,4° 
14 Copper - - 
82,10 
46 
36,10 
15. Standard silver 
85,4° 
82,90 
8,$0f 
16. Copper - - 
85 
82,40 
2,6'o 
17. Gold with copper 
i4°,3° 
1 17,10 
23,20 
18. Copper - 
82,30 
66,80 
15,5° 
19. Gold with copper - 
134,5° 
1344° 
<V*°J 
20. Standard silver - 
85,20 
83,20 
1 >.90 
* Increased in weight 0,40. 
f The piece of silver was slightly coated by the copper. 
J The standard gold was coated by the silver. 
