28 Mr. kirwan’s Experiments , &c. the fpecijic Gravities ■ 
fpecific gravity by obfervation is 1,819, be found, to ffe 
6 £ 
p-^~ = 3,66 4; but of this 2,95 gr. are the lofs of the water it 
contains, and the remainder 0,714 * are the lofs of the mere 
acid part. Then, = 4,9649 is nearly the true fpecific gra- 
vity of the pure vitriolic acid. 
I then found the true increafe of denfity arifing from the 
union of the vitriolic acid and water in the foregoing- mixtures, 
and obferved, that in oil of vitriol, whofe fpecific gravity was 
1,771, it was 0,84, and in that whofe fpecific gravity was. 
1,719, it was 0,100. 
To obtain a fynthetical proof of thefe deductions, I compared 
them with the fpecific gravities of the firfl mixtures I had made ; 
for if thefe deductions were true, the mathematical fpecific gra- 
vities, and the accrued densities, added to each other, fhould 
amount to the fame quantity as the fpecific gravities by obferva? 
tion ; and this I found to happen very nearly ; for in the firft 
experiment, where 2519,75 gr. of oil of vitriol, whofe fpecific 
gravity was 1,819, were mixed' with 180 gr. of water, that oil 
of vitriol contained by my calculation 1376,1.71 gr. of acid and 
1 145,597 g r * water 5 befides the 180 gr. of water that were 
added to it, the lofs of the acid was ~ 277,22. The 
4 > 9°4 
whole quantity of oil of vitriol was 269.9,75 gr. ; then the 
fum of the Ioffes was 1600,81 ; and therefore the mathemati- 
cal fpecific gravity 7— ^ 1,686; to which, adding ,0-84 the 
degree of accrued' denfity, the fpecific gravity by obfervation 
* By miflake, the following calculations were made on the fuppofit'ion that the 
lofs was 0,715 ^ the difference being immaterial^ the calculations were not 
repeated. 
1 
fhould 
