on Spirituous Liquors* 
taking the weight of a gallon of water at the fame heat to be 
8 lb* 5,66 &c. 0%. *1 the fpecific gravity of this diluted fplrit will 
be found ,9335 at 6o° f ; whence, by a computation founded 
on the tables in this Report, the fpecific gravity of proof 
fpirit will come out ,916. But the rulers of correction be- 
longing to Dioas’s and Quin’s hydrometers give the fpecific 
gravity of proof fpirits about ,922 at 55°, equivalent to ,920 at 
6oh The former, ,916, correfponds to a mixture of 100 parts 
of fpirit with 62 by meafure, or 75 by weight, of water; and 
the latter, ,920, to a mixture of loo parts of fpirit and 66 by 
meafure, or 80 by weight, of water. The difference is con- 
fiderable; but the firft is undoubtedly moft conformable to the 
exifting Ads of Parliament. If, therefore, it be thought right 
to preferve the term proof-fpirit in our Excife Laws, it may 
be underftood to mean fpirit, whofe fpecific gravity is ,916, 
and which is compofed of 100 parts of redified fpirit at ,82c. 
and 62 parts of water by meafure, or 75 by weight ; the whole 
at 60 degrees of heat. 
I have chofen this point of the thermometer, 6o°, in pre- 
ference to 55°, becaufe it Is much the moft fuitable for experi- 
ments, being the temperature at which a room feels pleafant, 
and in which any operation, however flow and tedious, can be 
executed without the uneafy fenfation of cold : for this reafon 
it has been adopted by many Englifh philofophers. In the 
table formerly recommended, from 40 to 80 degrees of the 
thermometer, it will be the middle temperature. 
* Probably 8 lb . 5,^2 oz. is nearer* 
f This fpecific gravity indicates a mixture of 107 grains of water with 100 
of fpirit, and confequently is below Mr. Gilpin’s prefent Tables, which go only 
to equal parts. 
y 
The 
