1 8 Mr. kirwan’s Experiments , &c. on the fpccifc Gravities 
fait, vvhofe fpecific gravity is 1,098, that is, 3,55 gr. ; the 
remainder of 11 gr. is therefore mere water, viz. 7,45 gr. ; 
confequently, if the denfity of the acid and water had not been 
increafed by their union, the fpecific gravity of the pure and 
mere nitrous acid fhould be 11,8729; for the fpecific gravity 
of this acid Ihould be as its abfolute weight divided by its lofs 
of weight in water, and this lofs fhould be as the total lofs of 
thefe 1 1 gr. minus the lofs of the aqueous part. Now the total 
lofs = ^^=1 7,749, and the lofs of the aqueous part = 7,45, 
and confequently the lofs of the acid part is 7,749 — 7>45 — 
0,299, anc ^ therefore the fpecific gravity of the acid part, that 
is, of the pure nitrous acid, is 1 158729. 
But it is well known, that the denfity of the nitrous acid, 
as well as that of the vitriolic, is increafed by its union with 
wate* ; and therefore the lofs above found is not the whole of 
its real lofs in its natural ftate (if it could be fo found), but partly 
the lofs that arifes from the denfity that accrues to it from its 
union with water : for fince its denfity is increafed by this union, 
its lofs is lefs than it would be if the nitrous acid had only its 
own proper denfity, and confequently the fpecific gravity above 
found is greater than its real fpecific gravity. 
To determine, therefore, the real fpecific gravity of this acid 
in its natural flate, the quantity of accrued denfity muft be 
found, and fubtradted from the fpecific gravity of the fpirit of 
nitre, whofe true mathematical fpecific gravity will then ap- 
pear. I endeavoured to effedl this by mixing different portions 
of fpirit of nitre and water, remarking the diminution of their 
joint volume below the fum of the fpaces occupied by their fe- 
parate volumes ; but could never attain a fufficient degree of 
precifion. 
