specific Gravity , and comparative Wear of Gold. 167 
Table VI. 
Number of revolutions, 220000. 
Quality. 
Weight be- 
fore friction. 
Weight after 
friction. 
Loss. 
Grains. 
Grains. 
Grains. 
1. Gold made standard by fine 
Swedish copper, 4 pieces, 
unstamped 
48 7 ’9° 
487,90 
2. Gold made standard by fine 
Swedish copper, 4 pieces, 
stamped - - 
486,30 
484 
2,30 
3. Gold made standard by 
equal parts of fine Swedish 
and dollar copper, 4 pieces, 
unstamped 
564,7° 
564,70 
4. Gold made standard as a- 
bove, 4 pieces, stamped 
564>30 
550,40 
13,90 
5. Gold with fine copper, 2 
pieces, unstamped 
244 
243,90 
0,10 
Gold with fine and dollar cop- 
per, 2 pieces, unstamped 
285,50 
285,50 
_ 
6. Gold with fine copper, 2 
pieces, stamped 
239,50 
233,60 
5,9 0 
Gold with fine and dollar cop- 
per, 2 pieces, stamped -- 
279,90 
276,50 
3,40 
This experiment proves, 
1st. That very ductile standard gold, when exposed to the 
friction of gold of a similar quality, suffers less by abrasion than 
gold which is comparatively brittle, or harder, and which is sub- 
jected to friction under the same circumstances. 
edly. That when soft gold and brittle or hard gold rub against 
