54 
stemme de her beskrevne Resultater kun maadeligt overens. 
Ifølge den af Wackerbarth efter Ekmans Observationer 
beregnede Formel er Temperaturen for Tæthedsmaximum 
hos Søvand af Egenvægt 1.02707 = — 4 .' " 04 . medens Lig- 
ningen ^ = 0 med de af mig fundne Coefficienter giver 
Temperaturen — 4 ." 45 . 
Paa Grund af denne gjennemførte Overensstemmelse 
mellem Ekmans og mine Resultater, har jeg ikke fundet 
det fornødent at bestemme Udvidelsen af Vandprøver af 
lavere Egenvægt, men har uden videre anvendt Ekmans 
Observationer paa de faa Puncter, hvor jeg til Reduction 
af de paa den norske Nordhavsexpedition aflæste Egenvæg- 
.ter har havt Brug for dem. Yed Hjælp af de ovenfor op- 
førte Værdier for Søvandets Volumina ved forskjellige 
Temperaturer kan man nu beregne de Correctioner, hvor- 
med de ved vilkaarlige Temperaturer aflæste Egenvægter 
1 7 °5 
maa forbedres forat reduceres til ' . Correctionerne . 
1 <.°o 
hvori ogsaa indgaar et Led. der afhænger af Aræometrenes 
IJdvidelsescoefflcient. 1 Andes sammenstillede i nedénstaaende 
Ta bel. 
t° 
Correction 
t° 
Correction 
0 
— 0.00224 
12 
— 0.00104 
2 
— 0.002 14 
— 0.00069 
4 
— 0.00201 
l6 
— 0.0003 1 
6 
— 0.00183 
l8 
0.0001 1 
8 
— 0.001 61 
20 
0.00056 
10 
—0.00134 
Hvor den Temperatur, hvorved Aflæsniugeh foretages, 
ikke fjerner sig meget fra Normaltemperaturen 17 .° 5 , kan 
disse Correctioner, der strengt taget kun gjælde for Søvand 
af Egenvægt omkring 1 . 027 . ogsaa uden mærkelig Feil an- 
vendes i or \ andprøver af en derfra temmelig forskjellig 
Egenvægt. Hvor derimod den Temperatur, hvorved Aflæs- 
ningen foretages, ligger langt fra 17 .° 5 , ere disse Correc- 
tioner kun gyldige for et meget begrændset Interval. 
Elterat saaledes de aflæste Egenvægter ved Anbrin- 
gelse af disse Correctioner ere reducerede til Normaltem- 
peraturen. staar det endnu tilbage at befrie dem for de ved 
de benyttede Aræometre heftende constante Feil. 
Til Aflæsning af saa godt som alle paa Expeditionen 
bestemte Egenvægter benyttedes kun 3 Aræometre, to paa 
tørste Togt og et paa de to sidste. Af de to først nævnte, 
tier af Svendsen for Udreisen vare udvalgte af de øvrige, 
fordi de -havde vist sig at stemme særdeles vel ovetfens, er 
desværre det ene senere bleven knust, det andet er endnu 
i Behold og er. sammen med det paa sidste Togt benyttede 
bleven corrigeret af mig. 
1 Som saadan benyttedes 0.000020. 
A. Wackerbarth from Ekmans observations, the tempera- 
ture for the maximum density of sea-water with a specific 
gravity of 1.02707 is — 4 . " 04 , whereas the equation ~ = 0 
gives, with my coefficients, a temperature of — 4 .° 45 . 
Relying, then . on the close agreement between 
Ekman’s results and my own. I have not determined 
the expansion in samples of sea- water with a lower 
specific gravity, but have adopted Ekman’s observations, 
for reducing, when needful, the specific gravities read on 
the Norwegian North- Atlantic Expedition. By means of 
the values, tabulated above, for the volume of sea-water at 
I . different temperatures, the corrections which serve to reduce 
1 7 "5 
specific gravities read at. any given temperature to 7 ~- 
1 i ,°o 
may be computed. These corrections, into which the coef- 
ficient of expansion of the areometer 1 enters as- a factor, 
are given in the following Table. 
t° 
Corrections 
t° 
Corrections 
0 
— 0.00224 
12 
— 0.00104 
2 
— 0.002 1 4 
14 
— 0.00069 
4 
— 0.002O1 
16 
— 0.0003 1 
6 
— 0.00183 
18 
0.0001 1 
8 
— 0.001 61 
20 
0.00056 
10 
— 0.00134 
When the temperature is not far removed from the 
normal temperature, 17 . " 5 , these corrections, which, strictly 
speaking, apply only to sea-Vater with a specific gravity 
ol about 1 . 027 , may, without involving . any appreciable 
error in the result, be likewise adopted for samples of 
water whose specific gravity differs considerably from that 
expressed by the above formula; but when, on the other 
hand, the temperature at which the specific gravity is read 
and that of 17.° 5 lie far apart, the interval for which these 
corrections will serve is but very limited. 
After reducing by means of these corrections the 
specific gravities to the normal temperature, there still 
remains to eliminate the constant error of the areometer. 
For reading almost all of the specific gravities determ- 
med on the Expedition, only 3 areometers were made use 
of. two on the first cruise and one oil the two last. Of 
the two former, which, having been found to agree uncom- 
monly well, Mr. Svendsen had selected previous to his 
departure, one was unfortunately afterwards broken; the 
other is still in perfect order, and was, together with that 
made use of on the last voyage; corrected by myself. 
1 That adopted was 0 . 00002 ( 1 . 
