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pegede, og det er derfor helt naturligt, naar
Undersøgelserne ikke i Henseende til Studiet af tidligere ukjendte
Eiendommeligheder ved Havet kunde føre til saa fyldige
Resultater, som ønskeligt kunde være. Men om end disse
Undersøgelser paa Grund heraf nærmest faa Karakteren af
forberedende Arbeider, saa vil det dog, som jeg haaber,
indrømmes, at de desuagtet kunne have sine maaske ikke
uvigtige Følger, idet de vise, at man gjennem de chemiske
Observationer, der tidligere i Sammenligning med Tempe- ,
ratur- og Dybdebestemmelser har spillet en mindre
fremtrædende Rolle ved Studiet af Havets Physik, vil kunne
skaffe Oplysnyiger om mærkelige Forholde i Havet, som
man ad anden Yei vanskelig skulde falde paa at søge
opklarede. Man vil ved Hjælp af de her erholdte Resultater
med Lethed i Fremtiden kunne udkaste en detailleret’Plan
for en fornyet Undersøgelse af det norske Hav, der i mine
Øine stiller sig som særdeles ønskelig, da man ved at gjøre
et hidindtil ukjendt Hav til Gjenstand for Bearbeidelse
vanskelig turde gjøre Regning paa at træffe et, der i
Henseende til Studiet af Strømforholdene er saa instructivt
som det norske Hav.
Ved saadanne fremtidige Undersøgelser kunne de paa
den norske Expedition benyttede Arbeidsmethoder ikke i
alle Retninger blive optagne i uforandret Form, og dét vil
derfor ikke være ubeføiet til Slutning med faa Ord at
paapege de Mangler, der klæbe ved disse.
De til Saltbestemmelserne tidligere benyttede
Methoder, ifølge hvilke alle herhen hørende Observationer
anstilles ombord, bør utvivlsomt for Fremtiden ikke komme
til Anvendelse, da man ad den Yei tiltrods for al anvendt
Møie ikke vil kunne opnaa den Nøiagtighed, som tiltrænges
for med ønskelig Sikkerhed at kunne paavise de i Havet
forekommende ofte meget smaa Differentser. Paa den
norske Expedition blev denne Fremgangsmaade benyttet,
fordi man med ældre Iagttageres Udtalelser for Øie maatte
befrygte, at Søvand ikke lod sig opbevare i længere
Tidsrum uden at undergaa forskjellige Forandringer, en Frygt,
der imidlertid efter min Erfaring kun forsaavidt er
begrundet. som man til Opbevaring af Vandet benytter Kar,
der ere forsynede med Korkeprop. Jeg har nemlig
undersøgt flere Vandprøver, der have været opbevarede paa
denne Maade i omkring 2 Aar og fundet, at de alle uden
Undtagelse have undergaaet Forandringer af saadan Art,
at man turde være berettiget til at anse dem uskikkede
til Egenvægtsbestemmelse, hvorimod jeg hos Vandprøver,
der i lignende Tidsrum havde henstaaet paa Flasker
forsynede med isleben Glasprop, ikke kunde opdage
nogensomhelst Eiendommeligheder, eier kunde adskille dem fra
friskt øste Vandprøver. Ved denne Opbevaringsmaacle
risikerer man dog ganske sikkert Fordunstning af en Del
af Vandet, og man maa derfor beskytte sig mod denne
Feilkilde ved at hjemføre det til Saltbestemmelser
bestemte Vand paa tilsmeltede Glasrør.
I de saaledes conserverede Vandprøver vil man
senerehen efter Hjemkomsten kunne bestemme Egenvægten ved
Sprengels Pyknometer og Chlorgehalten ved Hjælp af
Vei-ningsanalyser metl saadan Skarphed, som man ved Arbeide
servations, and hence the results of the work done,
embracing as it did the investigation of phenomena unknown
before, were naturally less comprehensive than might
otherwise have been attained. But, though such labours must
to a certain extent, be regarded as preliminary, they will,
I trust, prove of considerable importance, showing as they
do, that chemical observations, which, as compared with
determinations of temperature and depth, previously held
quite a subordinate rank among the means employed for
studying the physical conditions of the ocean, will serve to
throw light upon many remarkable phenomena, that without
such data would be extremely difficult to explain. On
the basis of the results here set forth, a detailed plan
might be easily laid down for the further exploration of
the Norwegian Sea, — in my opinion a most desirable
undertaking, since of ocean tracts as yet Unknown, there are
probably few that, in regard to the study of ocean
currents, would so well repay investigation as that section of
the North-Atlantic.
As several of the methods of investigation practised
on the Norwegian Expedition, will not admit of being
adopted on future occasions in a wholly unmodified form,
it will not be out of place in conclusion briefly to point
out their defects.
The methods previously devised for determining the
amount of salt in sea-water, by which all observations with
this object in view were taken on board, should
unquestionably cease to be adopted, since they will not suffice, with
the greasest care even, to attain the high degree of
accuracy requisite for detecting such minute differences as are
frequently found to occur. These defective modes of
operation were, however, adopted on the Norwegian
Expedition, there being reason to believe from, the statements of
earlier observers, that sea-water could not be preserved
for any length of time without undergoing chemical change,
a supposition which, so far as my experience goes, is
confirmed only in the event of its being kept in corked vessels.
I have examined, for instance, various samples of sea-water
that had been preserved for about 2 years in corked bottles,
and found all without exception to have undergone a change
sufficient to render them unfit for specific gravity determ-.
inations; whereas, 011 the other hand, sea-water which had
been allowed to stand over for the same space of. time in
bottles furnished with ground glass stoppers, was not to be
distinguished from freshly drawn samples. There is,
however, a risk of loss from evaporation, the stoppers being
seldom, if ever, tight-fitting; and to guard against this
source of error, the water for salt-determinations must be
brought home in hermetically sealed glass tubes.
With water thus preserved, the specific gravity may
be determined by means of Sprengel’s pycnometer, and the
’amount of chlorine by weighing, on the return of the
Expedition, far more accurately than would be possible on
11 *
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