Spe-cif′ic-grav′i-ty Bal′ance.
For determining specific gravities.
The arrangement (
Fig. 5.52) illustrates the principle discovered by
Archimedes, that every body immersed in a liquid loses a part of its weight equal to the weight of the liquid displaced.
See page 2255.
From one of the scale-pans of an accurate balance is suspended a hollow cylinder of copper, and beneath this a solid cylinder of the same metal precisely equal in volume to the interior of the upper cylinder.
These are balanced by weights in the other scale-pan, and the solid copper cylinder is then immersed in a vessel of pure water.
This disturbs the equilibrium of the scale, which is again restored by pouring water in the upper cylinder.
The quantity required is exactly equal to that displaced by the lower cylinder, and its weight divided into that of the latter gives the specific gravity of the copper.
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Specific-gravity balance. |
In the case of liquids, a body not liable to be attacked by the liquid is suspended from one of the scale-pans.
The body is weighed first in the liquid to be examined, and afterward in water.
The weight in water divided into the weight in the other liquid gives the specific gravity of the latter.
See “
Mohr's specific gravity balance,” pages 39, 40, “
Griffin's chemical handicraft.”
