172 Mr. Hatchett’s Experiments on the various Alloys , 
and, allowing that to be the case, such a difference cannot be 
deemed worthy of notice. 
Before the observations upon the foregoing experiment are 
concluded, it may be proper to add, that no essential difference 
between plain and stamped pieces could be observed, when 
friction was applied in the way abovementioned. 
Here terminated the experiments which were intended to 
ascertain the effects arising from the friction of coin against 
coin; but it will probably be better to postpone the general 
observations upon this part, until the experiments have been 
described which were made with the machine Fig. 3. 
By this apparatus, which may be called No. 3, various pieces 
were exposed to the action of certain powders and filings of 
metals, which were separately sprinkled upon the horizontal 
table. 
The pieces were properly fixed in their respective sockets and 
frames, and were placed so as to bear upon the table, with or 
without additional weights. 
The table was moved by a wheel and pinion, so calculated as 
to avoid too rapid a motion ; and the revolutions were denoted, 
as in the former experiments, by means of a counter. 
Experiments made with the Machine No. 3. 
In the first experiment which was made with this instrument, 
the table was covered with fine powdered whiting, and the 
pieces were arranged as follows* 
* Two pieces of each of the different kinds of gold, &c, were subjected to this 
experiment. 
