[ 47 * ] 
niuft be allowed bcftdes, that 60 Grains of Mer- 
cury take up too fmall a bulk in thefe Fluids, to 
have their gravities determined with any exadnefs 
thereby. 
As Profeffor Mufschenbroek has given in his table 
the fpecific weights of many of the fame falts 
which are mentioned by Dr. Freind , but which dif- 
fer confiderably from the weights above fet down, 
as refill ting from the Dodoi's experiments, I have 
alfo tranlcribed the Profeffor’s numbers from his 
own table. Thefe do not however appear to me 
to be derived from new or differing experiments, 
but from the very fame related by Dr. Freind , only 
computed from the fuppofition of a heavier Tort of 
Spirits of Wine, whofe fpecific gravity is fuppofed 
to have been 0.823. The gravity of the Sublimate 
corrojive , fet down 8.000, I take to be a miftake, 
made by the writing down its comparative weight to 
that of the Spirits themfelves, inftead of the water to 
which it fhould have been referred. 
It requires great care and attention to take the 
Specific Gravities of Salts with fufficient accuracy. 
They diffolve in Water, and in fome degree in all 
Fluids that partake of the nature of Water. If 
therefore Spirits of Wine are made ufe of for this 
purpofe, they ought to be highly redified, their own 
gravity accurately afeertained, and their degree of heat 
fhould be preferved uniform. For as this Fluid rare- 
fies much fatter than Water does, a fmall difference 
of heat would fenfibly affed the gravities of the Salts 
to be determined by ir. And perhaps Spirit of Tur- 
pentine were a more proper Fluid to be employed 
on thefe occafions. 
it 
