138 Mr. Hatchett’s Experiments on the various Alloys , 
SECTION III. 
ON THE COMPARATIVE WEAR OF GOLD, WHEN ALLOYED BY 
VARIOUS METALS. 
The comparative wear of gold, especially when in the form 
of coin, has never yet been ascertained; the opinions con- 
cerning it are therefore various. The most prevalent idea ap- 
pears to be, that pure or ductile gold suffers more in a given 
time, under equal circumstances, than that which is of a harder 
quality. 
Supposing this fact to be well established, it would not be 
difficult to render gold as hard as could be desired; for, as 
certain metals, when employed in equal proportions, cause gold 
to become of very different degrees of hardness, it would be 
easy even to make gold perfectly hard and brittle, without 
changing the standard proportion of alloy, provided that such 
extreme hardness was compatible with the process of coining. 
But the question, whether ductile or hard and brittle gold 
sustains the greatest loss by wear, under equal circumstances', 
has by no means been fully determined ; and Mr. Harris ap- 
pears to have considered hard metal as the most liable to suffer, 
it being, when compared to that which is pure and soft, more 
brittle and less tenacious.'* 
Gold, when in the form of coin, appears to be generally ex- 
posed to three varieties of friction, viz. 
1st. Friction between pieces of gold coin of a similar or of a 
different quality. 
An Essay upon Money and Coins, 1758, Part II. page 117. 
