On Specific Gravity: 123 
solid matter: but, no sooner is a body, which hasbeen intros . 
duced into a liquid, withdrawn, than the aliquid. is found to fill. 
up the space from which it has been removed. 
It is evident, that the force which eauida wei: thus to re- 
enter any space within them, from which they are forcibly 
isplaced, is precisely equal to the weight of a quantity of 
the liquid, poeanersar ne with that space; since, when the 
is re-occu y the liquid, the equilibrium is restored. 
Consequently, every body, introduced into a liquid, experi- 
ences from it a resistance equal to the weight of a quantity of 
the liquid; commensurate with the cavity, which would be 
produced, supposing the liquid, frozen about the solid mass, 
split open so as to remove it, and the fragments put together 
again : and the cavity also ps created, must. obviously be 
exactly equal to the bulk of the body. It follows, that the 
resistance which any Bode encounters in ing, within a 
fluid, is equivalent to the weight of a quantity of me! soa in 
bulk equal to the body. . 
To ascertain the specific gravity of a body heavier than water. 
Let the. body be the glass stopple, ‘represented, in the fol- 
Jowing figure. _ 
First counterpoise the stopple by means of 
a scale beam and weights, suspending it by a. 
fine metallic wire. Place under the stopple, a 
vessel of pure water, and lower the beam, so 
that, if the stopple were not resisted by the 
water, it would be immersed in that fluid. 
Add just as much weight, as will counteract 
immersi and render the beam; 
again horizontal. ae by which 
the stopple had .d been previously ounterpoised, 
by the weight thus employed to ‘sink i. 3: The 
quotient will be the specific gravity. 
Rationale. 
ahs weight required to sink the stopple, is. gee igo 
the bulk of water which the es. O 
pee to the general, rule, it is ‘only necessary to P44 
