and attraBive Powers of various fallne Subfances . i p 
precifion. The following method, though not exa 6 dy accurate, 
I found more fatisfidlory. 12 gr. of the fpirit of nitre, whofe 
fpecific gravity by obfervation was 1,389, contained as I fup- 
pofed from the former experiment 3,55 gr. of acid, and 8,45 
of Water ; then if the fpecif c gravity of the pure nitrous acid 
were 115872, the fpecific gravity of this compound of acid and 
water fhould be 1,371 ; for the lofs of 3, 5 5 gr. acid fhould be 0,29 9, 
and the lofs of the water 8,45 ; the fum of the lodes 8,749. b- 
1,371 ; but, as I already faid, the fpecific gravity by 
obfervation was 1,389, therefore the accrued denfity in this 
cafe was at lead ,018, the difference betwixt 1,389 and 1,371. 
1 fay at leaf , for as the fpecific gravity 11,872 was certainly 
too high, the lofs of 3,55 gr. acid was certainly too fmall ; 
and if it were greater, the mathematical fpecific gravity 1,371 
would have been frill lower. However, ,018 is certainly a near 
approximation to the degree of denfity that accrues to 3,55 
gr. acid by their union to 7,45 gr. of water, and differs inconfi- 
derably from the truth, as will appear by the fequel : therefore 
fubtradling this quantity from 1,419 we have nearly the mathe- 
matical fpecific gravity of that proportion of acid and water, 
namely, 1,401. And fince 1 1 gr. of this fpirit of nitre contain 
3,55 gr. acid and 7,45 of water, its lofs of weight fhould be 
p—. = 7,8 55, and fubtra&ing the lofs of the aqueous part from 
this, the remainder 0,405 is the lofs of the 3,55 gr. acid, and 
confequently the true fpecific gravity of the pure and mere ni- 
ry f g* 
trous acid is = 8,7654 : this being fettled, the mathema- 
tical fpecific gravity and true inereafe of denfity of the above 
mixtures will be found. Thus the mathematical fpecific gra- 
vity of 12 gr. of that fpirit of nitre, whofe fpecific gravity by 
D 2 obfervation 
