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L Om Luften i Søvandet.
I. On tlie Air in Sea-Water.
Allerede i lange Aarrækker har der fra Tid til anden af
forskjellige Chemikere været foretaget Experimenter i
den Hensigt at studere Forholdene ved den atiuosphan-iske
Lufts Absorbtion af de Vædsker, hvormed den i Naturen
kommer i Berøring, men det er dog først i de seneste Aar.
at dette Spørgsmaal har været gjort til Gjenstand for mere
omfattende Undersøgelser, hvad angaar Søvandet i de aabne
Have. Rigtignok foreligger der ogsaa fra ældre Tider
enkelte Opgaver over Sammensætning og Mængden af den i
Søvandet opløste Luft, men disse ere for det Meste bundne
til nogle ganske faa Puncter af Kysterne, og der. hvor
Forsøgene ogsaa omfatte Vandprøver fra det aabne Hav.
er der ofte saameget at indvende mod Materialets
Indsamling og Opbevaring, at man, selv om Intet maatte være at
udsætte paa Methoderne til dets Undersøgelse, ikke kunde
sætte disse i Klasse med de med vore Tiders fuldkomnere
Hjælpemidler udførte Observationer.
Naar saaledes vort Kjendskab til Fordelingen .af
Luften i Verdensha vene specielt for de store Dybs Vedkommende
lige til de seneste Aar maa siges at have været meget
mangelfuldt, da maa Grunden hertil søges i de mange
Vanskeligheder, som man allevegne møder, naar man vil
undersøge disse Spørgsmaal. Hvor det gjælder at bestemme
Sammensætningen af den atmosphæriske Luft, giver Luftens
Letbevægelighed Ilet til af Undersøgelser udførte paa faa
Puncter at slutte til den hele Atmosphære, hvad der
imidlertid ikke er Anledning til for Søvandets Vedkommende.
Der fordrer Havenes langt ringere Bevægelighed et større
Antal Observationer, idet der her maa stilles meget
strengere Fordringer til den geografiske Udbredning. Enten
maatte altsaa Vandprøver hjemføres fra fjerne Farvande,
saaledes at de ved en længere Tids Henstand udsatte for
allehaande fremmed Indvirkning kunde blive aldeles
ubrugbare, eller Analytikeren maatte, udsat for alle de Ulemper,
som et Skibs Bevægelser medfører for videnskabelige
Undersøgelser. forsøge bedst muligt at udføre sine
Observationer ombord. Men selv naar der hos mange Chemikere fra
ældre Tider kan have været Interesse for ved Undersøgel-
Dcn norske Nordhavsexpedition. Tornøe: Chemi.
Experiments have long since been instituted, from time
to time, by divers chemists, with the object of
investigating the absorption of atmospheric air by the thuds w ith
which in the course of nature it comes in contact: but not
till of late years has this phenomenon been made the subject
of exhaustive treatment in its relation to ocean-water.
True, there do exist comparatively early statements
respecting the amount and composition of the air present in
sea-water. hut the great majority ol’ such are Confined to a
very few coastal localities; and w hen, as was sometimes the
case, the samples of sea-water examined had been drawn
from the open sea. the mode ol’ collecting and preserving
them was frequently so open to objection that, even
assuming the methods adopted for their examination to
have-been in every respect trustworthy, these early experiments
will not bear comparison with those of modern date,
performed with the far superior apparatus since devised.
• Our knowledge therefore, till hilt a few years since,
of the distribution of air in ocean-water, must be said
to have continued very imperfect; and the reason is
found in the numerous difficulties everywhere encountered
when proceeding to investigate so intricate a subject. From
the great mobility of the atmosphere, experiments in a few
localities only will suffice to determine the general
composition of air; but with sea-water the case is different.
Water being far less fluid than air, many observations
are obviously needed, since the greatest importance
must be attached to geographical position. Hence,
samples ol’ sea-water had to be brought home from distant
x-egions. and in that case, by being allowed to stand over
for a comparatively long period, left exposed to all manner
of disturbing influences: or the observations were taken 011
board, and experiments performed to the best of the
analyst’s ability, in spite of the numerous drawbacks entailed
by the motion ol’ the vessel. But. though many of the
earlier chemists Would, when at sea. no doubt have felt an
interest in contributing to solve the problem of the
distribution of air in the water of the ocean, they almost inva-
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