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II. Experiments and Observations on the Specific Gravities and 
attractive Powers of various faline Subfiances . By Richard 
Kirwan, Efq . F. R* S. 
Read November 1 6, 17 8ov 
T HE doctrine of chymical affinities hath of late received 
great improvements from the labours of the very excel- 
lent Mr. bergman of Upfal, and the frill later refearches of 
Mr. wentzel ; but the order of thefe attractions has hitherto 
been the only point attended to by thefe philofophers, as well a& 
by mod: preceding chymids ; for I know of none, except Mr. 
morveau of Dijon, who has thought of afcertaining the va- 
rious degrees of force of chemical attraction, by which one 
body aCts on various other bodies, or even on the fame body 
in various circumdances. He has, however, fo ably (hewn the 
advantages arifing from fuch an inquiry, that I have made it 
the objeCt of my attention, and beftowed much pains on it for 
fome time pad ; and have been thereby enabled to determine 
pretty exaCtly the proportion of the ingredients of many neu- 
tral falts, and the fpecific gravity of the mineral acids in their 
pureft date, and free from all water. The principles on which 
thefe determinations are founded are the following. 
id. That the fpecific gravity of bodies is as their weight,, 
divided by the weight of an equal bulk of rain or diddled wa- 
ter, this being at prefent the dandard with which every other 
body is compared., 
2d 
