Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
Lg — Qq = — 0.0004598 Reg = — 0.0003776 Wulln.
tl = — 4°) A
t got ■” qpi = U.0000042 cc.
and
ti=—4°) Pl — p n
t _ _ ••• t __ t = U.006698 CC.
W = 0.0001740 [Reg] .... W = O.0001762 [Wiilln]
Difference .... = 1.2 %.
But it must be observed, that afterwards, when the volumes
of the liquid are determined with the same instrument,
the-relation
Lg — Qq = — 0.0004598 etc. . . .
holds good no longer. The volume of the water is diminished
by the melting, and consequently the volume of mercury in
the instrument is no longer Q but Qi. The above values for
liquid water then become
Lg — Qiq = — 0.0010409 Reg = — 0.ooo9654 Wfi]]n-
qpi = O.oooooo..........
ti = — I"! Pi—P n
t = o-|-tnt =-°-00"t«
w = — 0.0000767 [Reg] .... w = — O.oooo748 [Wiilln]
Difference .... = 2.5 %.
If the dilatometer is thus adjusted, so that for frozen water
Lg — Qq = 0 (or nearly 0),
it will perform its functions under more unfavorable 1
circumstances, if afterwards applied to determine the expansion of
the liquid water formed by melting of the ice.
The change of volume caused by the melting process is
naturally independent of all irregularities of this kind,
because the instrument is brought back again to its original
temperature after the melting is finished. The operation of
melting may therefore be considered to be accomplished at
constant temperature.
The principle of the artifice just described was originally
invented by Pliicker and Geissler.
C. Determination of the latent heat of water.
The method invented for this purpose is minutely de-
scribed in Journ. f. prakt. chem. [2] Bd. 24 p. 151 and must
1 I have chosen here the most unfavorable example, which can occur,
viz. the determination of the dilatation between 0° and — 1°.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
