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Every substance, as a rule, ought to expand its volume
when heated and contract it on cooling. Every exception to
this rule either in the apparent or in the real change of
volume is in this and subsequent tables denoted by the sign —.
As starting-point for my dilatometric experiments 1 I have
always chosen 0° C. The reason is obvious. This temperature
can be maintained steady as long as you please, if the
apparatus are surrounded with pure snow moistened with distilled
water. I consider it to be the natural starting-point of all
practical volumetric investigations, determinations of spec,
gravity, calibrations etc. Therefore the unit of all volumes
enumerated in this paper is 1 cc. of the liquid or solid
substance at 0° C. The specific gravity was always determined
by the Sprengel pycnometer at 0° C but afterwards referred
to that of pure water at + 4° by calculation. I denote this
by the sign
!l r<
+ 4°
I take a special pleasure in mentioning, that I had the
advantage of securing the assistance of my former companion
Mr. Larson in a part of the foregoing and also of the
subsequent series of determinations. At my wish Mr. Larson
undertook the leading of experiment I and likewise of V in
the next chapter. With the assistance of Mr. Larson I found
it possible to take the observations at regular thermometric
intervals of temperature.
1 In order to give a clear view of the experimental proceeding, I will
here enumerate the weighing results belonging to I.
Weight of the mercury, which fills the dilatometer entirely
at 0° G ...................................................... 676.il«o grm.
Weight of mercury in the capillary tubes, the stem,
stopcocks etc. which are not exposed to changes of
temperature ............................................................. 7.413C »
L .......................................................... 668.7014 grm.
After the close of the experiments the weight of that
mercury, which together with the water filled the instrument
entirely at 0°, was found .................. = 189.6390 grm.
therefrom to deduct............................ 7.413c >
Q, ........................................ 182.2254 grm. 182.2254 grm.
Wi.......................................................... 486.4760 grm.
Weight of mercury imbibed through >b» at melting ................. 44.1144 grm.
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