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.
73
lidet luftholdige, medens de. der have absorberet sin
Luftmængde i de arktiske Egne. maa indeholde meget større
Mængder, og man vil derfor netop i de paa Expeditionen
udførte Gasanalyser have et fortrinligt Middel til at
controllen den forhen opstillede Hypothese, ifølge hvilken
enkelte Regioner af det iskolde Dyb skulde være opfyldt af
Vandmasser, der ialfald delvis havde atlantisk Oprindelse.
Forat vise Udfaldet af en saadan Control har jeg
tegnet Kartet No. III. hvorpaa efter samme Princip som det
ved Tegning af Kartet No. II befulgte findes afsat de i
Dybet fundne Kvælstofmængder udtrykte i CC. pr. Litre
reducerede til 0° og 760""" Tryk, ligesom der ogsaa ved
Siden af disse Tal findes opført den Temperatur, hvorved
Søvandet absorberer denne Kvælstofmængde, beregnet til
nærmeste hel Grad efter den af de tidligere bskrevne
Forsøg udledede Formel
N= 14.4 — 0.23 f.
Det siger sig selv. at disse Temperaturer ikke kunne
gjøre Fordring paa nogen stor Grad af Nøiagtighed, da en
forholdsvis liden Feil i Kvælstofbestemmelsen bevirker en
meget stor Feil i den deraf beregnede Temperatur. Der
findes saaledes flere Observationer, der give Temperaturen .
— 4". en Temperatur, der mig bekjendt ikke er observeret
i Havet. Dette vil dog ikke forekomme saa urimeligt,
naar man tager Hensyn til. at Søvand af —2° ved 780"""
Barometerstand absorberer en Kvælstofmængde, der paa
det Nærmeste gaar op til. hvad der i Ydertilfældene er
fundet.
Farvelægningen er her foretagen saaledes, at de Strøg,
hvor Kvælstofmængden er funden at være 14.4 CC. eller
derover, ere betegnede med blaa Farve, de Strøg, hvor
Kvælstofmængden ligger mellem 14.4 og 12.5 CC., med en
svag rød Farve, medens et mindre Parti, hvor
Kvælstofmængden er funden at ligge under 12.5.CC., er betegnet
med en noget kraftigere rød Farve. Betydningen af disse
Farver bliver ligesom i Kartet No. II den. at de røde
Farver bedække de Strækninger, hvor Vandet i mere eller
mindre Grad besidder atlantisk Karakter, medens den blaa
Farve tilhører de Vandmasser, der have absorberet sin
Kvælstofmængde ved en Temperatur af under 0°, og som
altsaa nærmest synes at hidrøre fra de arktiske Egne.
Ved at sammenligne Kartene No. II og III vil man
strax se, at Farvelægningen i disse i alt Væsentligt Viser
en særdeles stor Overensstemmelse, som paa mange Puncter
endog nærmer sig til Congruents. om man end ved
nærmere Betragtning vil finde, at disse Ligheder ikke gaa
igjen i alle Detailler, hvad man heller ikke paa nogen
Maade kunde vente. Grændserne bliver nemlig paa Kartet
No. III paa Grund af Observationernes Faatallighed meget
vanskelige at bestemme, ja der findes endog her paa
omkring den 65de Breddegrad et større Strøg, hvorom man
intet med Bestemthed kan slutte, da der under Analysen
tabtes en mindre Del af de Luftprøver, der vare bestemte
til at udfylde dette Hul. saaledes at den samlede
Luftmængde desværre ikke kunde maales. Desuden ere ogsaa
Observationsfeilene baade for Salt- og Kvælstofbestemmel-
Den norske Nordliavsexpedition. Ti>rnne: Chemi.
with that absorbed in the Arctic regions, wherefore the
analyses of gas performed on the Expedition furnish an
excellent means of testing the value of the hypothesis
according to which certain sections of the cold area are
assumed to be made up of water part of which at least
would seem to be of Atlantic origin.
To show the result of such a test, I have annexed a
third Plate (drawn on the same principle as Pl. II). in
which are given the different amounts of nitrogen present
in deep water, expressed in c.centim. per litre, reduced to
0° and a pressure of760mm. Along with these figures will
be found, too. the temperature at which sea-water absorbs
such an amount of nitrogen, computed, in whole degrees,
by means of the formula deduced from the observations
previously described, viz: —
N= 14.4 —0.23f.
These temperatures cannot of course pretend to any
high degree of accuracy, a comparatively small error in a
nitrogen-determination involving a very considerable error
in the temperature. Thus, for instance, several of the
observations indicate — 4°, a temperature which, so far as
I am aware, was not anywhere observed in the sea. Tliis,
however, will not appear so strange, if regard be had to
the fact, that sea-water of — 2°, at a pressure
corresponding to 780""", absorbs an amount of nitrogen which agrees
very closely with the highest found on the Expedition.
The sections in this Plate are coloured as follows:
those in which the amount of nitrogen was found to equal
or to exceed 14.4". blue; those in which it ranged from 14.4
to 12.5cc, light red; a somewhat deeper red serves to
indicate a small tract in which the amount of nitrogen did
not reach 12.5. Moreover, as in Plate II. the red colour
indicates water more or less distinguished by Atlantic
characteristics; the blue, water in which the nitrogen was
absorbed at a temperature below 0°, and which, therefore,
would seem to have derived its origin from some part of
the Polar Seas.
A comparison of Plates II and III will at once
show considerable agreement in the distribution of colour,
many of the sections almost coinciding; though, on closer
inspection this approach to congruity is not found to
characterise all details, which indeed there was no reason to
expect. In Pl. III. the limits proved exceedingly difficult
to define, owing to the limited number of observations;
nay. respecting an extensive tract near the 65th parallel
of latitude nothing definite can be inferred, part of several
samples of air, the analysis of which would have served
to fill up the blank, having been unfortunately lost, and
the total amount of air could not, therefore, be measured.
Besides, the errors of observation both in the salt and the
nitrogen determinations, are so considerable, when
compared with the minute differences in amount, that, in some
11
<< prev. page << föreg. sida << >> nästa sida >> next page >>
