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graphy, 1 felt convinced beforehand, that 110 valuable
observation of this kind could have escaped the notice of my
predecessors, and consequently was prepared to repeat their
determinations merely in order to verify the exactness of the new
methods, which I wished to introduce. In many respects I
found this opinion confirmed — not in all.
On the dilatation of pure liquid w7ater there have been
published many treatises by prominent authors. The numbers
derived from my own researches in Table I, B. do not claim
an}- superiority to those already published by Hällström,
Kopp, Pierre a. 0. On the contrary, I expressly wish to
call attention to the fact, that my dilatometer [see page 268],
if once adjusted for attaining the greatest possible accuracy
of determination of the volumes of ice, performs its functions
under somewhat unfavorable circumstances, if used to measure
the dilatation of the melted ice, but nevertheless I think, that
the close coincidence of the numbers in Table I, B. with the
results of Pierre, Kopp, Rossetti a. 0. will testify, that
the new instrument is not inferior to any hitherto used in
investigations of this kind.
Also with regard to the change of volume of pure water,
when transformed into ice [at 0° C], my experiment is to be
considered only as a repetition of the determinations of
Bunsen. 1 This might be foreseen, because in this peculiar case
the dilatometer performs its functions exactly in the same way
as the instrument described by Bunsen in Pogg. Ann. CXLI.
The measurements of the dilatation of pure ice hitherto
published cannot be compared to the determinations of Kopp
a. O. on liquid water in jioint of exactness — naturally on
account of the difficulty of the problem, whatever method
may be chosen for the experiment. Some of these previous
determinations may be mentioned here. It must be observed,
that the result is found to be different, if the measurement is
made on ordinary ice, which contains air (the determinations of
the coefficient of linear expansion) or on ice, which is entirely
free from air [the measurements of the cubic expansion].
Of the former kind there exists [besides some ancient
observations by PI acid us Heinrich2 ’and more recent by
1 The previous determinations [by Ermann, Kopp, Brunner a. 0.]
can be safely omitted here. The only result, which really can compete with
the determination of Bunsen, is that of Plucker and Geissler (Pogg.
Ann. LXXXVI), who found the increase of volume at 0° C = 0.091 95.
3 Bair. Acad. Phys. Abh. 1800; coefficient of exp. = O.000024.
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