APPENDIX A

313

The value of L is negligible. Calculating the approximate value
of C using Eq. (3) we have,

0.01005 X 307 + 0.02377 X 0.998

230.55 X 307 X 307 X U

Calculating now the hydrostatic head, using this value of C, we
have from Eq. (5)

, hi = 0.44 + 0.01 = 0.45.

Now p = 230.55 + 0.45 = 231.0 for the left limb or
= 230.57 - 0.45 = 230.1 for the right limb;

hence, on applying again Eq. (3) the true value of C becomes

C =

0.1005 X 307 + 0.02377 X 0.998
231 X 307 X 307

= 1.428 X 10~7.

EXAMPLE OF CALCULATION OF VISCOSITY AND FLUIDITY

Suppose that we assume that we had given the constants of
the apparatus, and that we desired to calculate out the viscosity.
We have hi = + 0.45, K = —0.79, so that the corrected pressure
is 231.0. We may now apply Eq. (1) at once, but advantages
may be obtained, without extra labor, by calculating the value
of P in the equation

Cpt - C'p/t = CPT

C'P

P = 7>-^

(U)

Ofc

which is evidently the pressure consumed in overcoming viscous
resistance solely. In this case 7^ = 1.76 hence P =229.2.

The fluidity <p is

<p = 77^- = - =99.5 c.g.s. units.

Instead of writing the viscosity as 0.01005 we prefer to multiply
by 100 and record the datum as 1.005 centipoises (cp), which keeps
most viscosities from becoming inconveniently small fractions
and it also makes the viscosities "specific/' referred to water at
practically 20°.

In scrutinizing the data heretofore published on viscosity one
is particularly interested in the magnitude of the kinetic energy
correction and it may be subject to slight changes in the future.

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