specific Gravity , and comparative Wear of Gold. 183 
violent action of the iron filings, resembling that of a rasp, was 
too powerful to be modified in any very perceptible manner by 
the different ductility of these pieces ; and, consequently, little or 
no variation in the wear could be observed, excepting in the 
pieces of gold reduced to 18 carats by copper, which, being hard 
when compared with the former, were in some measure better 
able to resist the effects of the filings. 
The following comparative Table of the four preceding expe- 
riments, will show, by the near agreement of their general 
results, that the wear of gold, when exposed to the friction of 
earthy powders, or metallic filings, is in proportion to the 
relative degree of ductility. 
Table XIV. 
Comparative Table of the Four preceding Experiments. 
Experiment l. 
Experiment ii. 
Experiment in. 
Experiment iv. 
Revolutions, 
i 1880. 
Whiting. 
Revolutions. 
88o. 
Sand. 
Revolutions. 
66o. 
Filings of 
Standard gold. 
Revolutions. 
4°4* 
Filings of Iron. 
Quality of the pieces 
of gold. 
Lost. 
Loss. 
Loss. 
Loss. 
Gold 23 car. \ 
grs. - - J 
Grains. 
Ill } 4.6o 
Grains. 
£lo } i«.» 
Grains. 
.?£ } 2 3 ’ 3 ° 
Grains. 
25 ) 52,20 
27,20 / * 
Gold made stand- \ 
ard by silver J 
%l } 3.40 
%fo } 34 .'° 
til } Mo 
20 1 , 
26,30 | 
Gold made stand- ] 
ard by silver and 1 
copper - - J 
°S } 
;j ,6 ° } 26,60 
IZll ) 43.90 
Gold made stand- 1 
ard by fine cop- l 
per - - J 
£ 1 *- 6 ° 
lf£ } W 
040 } * 
}«■» 
