A diagram is thus traced out, the ordinates of which
represent increments of volume, or, in other words, of weight of fluid
displaced--the zero line, or line corresponding to a ball in a liquid of
equal density, being previously traced out by revolving the drum without
attaching the ball of metal itself to the spring, but with all other
auxiliary attachments. By means of a simple adjustment the ball is kept
constantly depressed to the same extent below the surface of the liquid;
and the ordinate of this pencil line, measuring from the line of
equilibrium, thus gives an exact measure of the floating or sinking
effect at every stage of temperature, from the cold solid to the state
when the ball begins to melt.
If the weight and specific gravity of the ball be taken when cold,
there are obtained, with the ordinate on the diagram at the moment of
immersion, sufficient data for determining the density of the fluid
metal; for
W / W1 = D / D1
the volumes being equal. And remembering that
W (weight of liquid) = W1 (weight of ball) + x
(where x is always measured as +_ve_ or -_ve_ floating effect), there is
obtained the equation:
D1 x ( W1 + x)
D = --------------- .
W1
[TEX: D = \frac{D_1 \times (W_1 +x)}{W_1}]
The results obtained with metallic silver are perhaps the most
interesting, mainly from the fact that the metal melts at a higher
temperature, which was determined with great care by the illustrious
physicist and metallurgist, the late Henri St.
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