gS Mr. Hatchett’s Experiments on the various Alloys , 
which are neither sufficiently malleable to be rolled, nor suffi- 
ciently brittle to be reduced into powder; and this last difficulty 
most frequently occurs in mixed or alloyed metals. 
It is well known, that the specific gravity of an alloyed metal 
is seldom that which, by calculating the respective specific 
gravities and proportions of the different metals, would be the 
result ; on the contrary, the specific gravity of the alloyed mass, 
is frequently greater or less than it ought to be, according to 
calculation. 
This effect has been often noticed by various authors ; and it 
is not requisite that I should here repeat facts already so well 
established ; I have, however, thought it proper to state, in the 
following pages, the changes in specific gravity which took place, 
when gold was alloyed with different proportions of various 
metals. 
In the following experiments, I employed a very accurate 
balance, which was made for me by Mr. Haas, and which, 
when loaded with 1000 grains at each end, turned with of 
a grain. 
The vessel containing distilled water, at 6o° of Fahren- 
heit, was covered with flannel, in order to avoid, as much as 
possible, any change of temperature produced by the circum- 
ambient air ; and every other precaution was taken, as is usual, 
when such experiments are to be made.* 
* Each experiment was most commonly made upon one Troy ounce of alloyed 
metal ; but in some cases two ounces were employed. The different ingots and bars 
were also carefully examined, and were cut, in order to discover any cavities or air- 
bladders in their interior. 
