so Mr. kirwan’s Experiments , &c. o« the fpecific Gravities 
obfervation was 1,389, mu ft be 1,355, fuppofing it to contain 
3,55 gr. acid and 8,45 of water ; for the lofs of 3,55 gr. acid is 
^4 = 0,405, and the lofs of water 8,45 ; the fum of thefe 
lolles is 8,855. Then, g-^ = 1,355, and confequently the ac- 
crued denfity is 1 ,389 ~ 1 ,355 = ,034. In the fame manner it 
will be found, that the mathematical fpecific gravity of 13,08 
gr, of that fpirit of nitre, whofe fpecific gravity by obfervation 
was 1,362, muft be 1,315, and confequently its accrued den- 
fity ,047. 
But the whole ftill refts upon the fuppofition that each of 
thefe portions of fpirit of nitre contain 3,55 gr. of acid. To 
verify this fuppofition, I could' think of no better method than 
that of examining the mathematical fpecific gravities of the 
ftrft mixture I had made of fpirit of nitre and water in large 
quantities ; for if the mathematical fpecific gravities of thefe 
agreed exactly with thofe of the quantities I had fuppofed in 
fmaller portions of each, I could not but conclude, that the 
fuppofitions of fuch proportions of acid and water, as I had 
determined in each, was juft ; and that this was the cafe will 
appear by the following calculations. 
1 ft. When to 1963,25 gr. of fpirit of nitre, whofe fpecific 
gravity was 1,4x9, 179? 5 g r * of water were added, the quan- 
tity of acid upon the above fuppofition ihould be 634,53 gr. ; 
for 11 . 3,55 :: 1963,25 . 634,53 . the quantity of waterin 
thofe 1963,25 gr. of fpirit of nitre fhould then be 1328,72, and 
after adding 179,5 gr. of water, the whole quantity of acid 
and water fhould be 2142,75, the lofs of acid was Tr~f~ ~ 
,24, and the fum of the Ioffes 1 580,46 : then the mathematical 
fpecific 
