g6 Mr. Hatchett’s Experiments on the various Alloys , 
SECTION II. 
ON THE SPECIFIC GRAVITY OF GOLD, WHEN ALLOYED BY 
VARIOUS METALS. 
The many difficulties which attend the making of experiments 
intended to ascertain the specific gravity of bodies, with any 
tolerable degree of precision, are sufficiently known to every 
one who has had practical experience ; and some of these diffi- 
culties have been ably pointed out, and avoided, by Sir George 
Shuckburgh Evelyn, Bart. F. R. S. in his valuable Paper, 
entitled An Account of some Endeavours to ascertain a standard 
of Weight and Measure. Phil. Trans, for 1798, p. 133. In 
fact, when we consider the inaccuracies of balances, and the 
effects produced by the different height of the column of water, 
and by the changes of temperature to which the water is 
exposed during the experiments, we have less reason to be 
surprised at the frequent variations in the results ; and, in addi- 
tion to these sources of error, if we consider the different 
texture of bodies, and the numberless interstices of them, often 
unequally arranged, and which cannot at all times be penetrated 
by water, we may rather wonder that so much precision has 
been attained. The last-mentioned obstacles to exactitude in 
such experiments, are peculiarly to be observed, when the spe- 
cific gravity of certain substances, such as stones and ores, is to 
be determined ; and, although the metals, being in general more 
dense, are supposed to be less liable to such variations in internal 
texture, yet it is acknowledged, that the specific gravities of 
these, as stated by various authors, cannot be regarded as exact ; 
and indeed, from the following experiments, I think it will 
