on the Specific Gravities , &c. oj Saline Subjhmces. 1 8r 
mixtures much denfer than when I fir ft examined them, and; 
that at leaft twelve hours reft was requiftte before concentrated 
oil of vitriol, to which- even twice its weight of water is 
added, attains its utmoft denfity, and ftill more when a lefler 
proportion of water is uled : thus, when I made the mixture 
of 2519,75 gr. ot oft of vitriol, whofe Ipecihc gravity was- 
1,819, with 180 of water, 1 found its denfity fix hours after 
1,771 ; but after twenty-four hours it was 1,798 : and hence,, 
according to the reafoning in the former paper, the accrued den- 
lity was at leaft ,064 inftead of ,045 as I had formerly found 
it. But by ufing oil of vitriol ftill more concentrated, whole 
fpecifc gravity was 1,8846, I was enabled,, by a fimilar train 
of reafoning, to make a ftill nearer approximation, and found 
that the accrued denfity of oil of vitriol, whofe fpecifc gra- 
vity is 1,819, am o unts to 0,-104; and confequently its mathe- 
matical fpecifc gravity is 1,715. 6,5 gr. of this oil of vitriol 
contained, as I before found, 3,55 of mere acid, and the re- 
mainder water, then the weight of an equal bulk of water is 
3,79 g r -r and fubtradting from this the weight of the water 
that enters into the compofttion of the oil of vitriol, it will be 
found, that the weight of a bulk of water, equal to the acid 
part, is 0,84, and confequently the fpecifc gravity of the 
pure and mere acid part is 4,226. Upon this ground, and 
conftantly allowing the mixtures to reft at leaft twelve hours 
(until the oil of vitriol was diluted with four times its weight 
of water, and then often only fix hours) before their denlity 
was examined, I conftrudted the table hereto annexed ; the tem- 
perature of the room I conftantly kept between 50 and 6o°. 
