C 4-34 ] 
fitter for thefe enquiries, than any others which had 
probably ever before been ufed for the fame pur* 
pofe, fo the known accuracy of the author, the 
goodnels of his inftruments, and the confiftency of 
all his experiments, fufficiently fhew the fpecihc gra- 
vities he has delivered in his paper, may entirely be 
depended upon. 
The fame curious perfon alfo communicated the 
Specific Gravities of fine and fiandard Gold, publifhed 
under his name in the following tables, and which 
were deduced from experiments he was fo kind as 
to make on purpofe at my requeft. 
As I have juft had occafion to mention Diamonds, 
it may poflibly not be foreign to the purpofe here 
to take fome notice of the Diamond Carat weight, 
ufed among jewellers, which weight was originally 
the Carat or 144 th P art °f the Venetian ounce, equal 
to 3,2 Troy Grains, but which is now, for want of 
an acknowledged fiandard, fomewhat degenerated 
from its firft weight. I have myfelf found it, upon 
a medium of feveral experiments, equal to 3,17 Troy 
Grains ; and I have the rather taken notice of this 
weight here, becaufe there happens to be a miftake 
about it, both in Dr. Ar but knot’s and Mr. Dodforis 
tables, who have fet down as it feems the number 
of Diamond Carats in a Troy Ounce, inftead of the 
weight of the Diamond Carat itfelf. This Carat is 
again divided into four of its own Grains, and thofe 
into halves and quarters, commonly called the eighths 
and fixteenths of a Carat: and thus the largcft of the 
Diamonds juft above-mentioned, weighed, in the 
jewellers phrafe, better than 29 Carats and almoft 
half a Grain. 
2 
Mr. 
