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29
ikke ved fortsat Inddampning skulde kunne have erholdt
et større Udbytte af Kulsyre. De af Dr. Jacobsen og
•J. Y. Buchanan udførte Observationer kunde derimod ikke
saa ligefrem forkastes, idet der jo kunde tænkes Mulighed
for, at det ved de af dem benyttede Methoder kunde have
lykkedes ved den langvarige Kogning at uddrive ogsaa al
neutralbunden Kulsyre, i hvilket Fald de af dem opførte
Tal i en anden Henseende kunde faa Betydning nemlig
som Udtryk for den samlede Sum af den i Søvandet
indeholdte Kulsyre.
Desværre .lagde liere Omstændigheder Hindringer i
Veien for Afslutningen af mine Forsøg over disse
Gjenstande i Vinteren 1877—78, dels var min Tid optaget med
andre Arbeider, dels lod min Helbred den største Del af
Vinteren adskilligt tilbage at ønske, saaat mine Forsøg
ingenlunde havde den ønskelige Fremgang, og jeg blev
derfor nødt til at gaa ucl ogsaa paa Togtet i 1878 uden nogen
paalidelig Methode til Bestemmelse af den i Søvandet
indeholdte Kulsyre. Da jeg efter endt Togt om Høsten vendte
tilbage, gjenoptog jeg imidlertid atter mine Undersøgelser
og bragte dem til Afslutning.
Gjennem en netop da af C. Borchers offentliggjort
Afhandling! om Bestemmelsen af Kulsyren i naturlige
Mineralvande blev jeg gjort opmærksom paa det for
Bestemmelse af Kulsyren i Carbonater af Alexander Classen angivne
Apparat,- so ni jeg senere i stor Udstrækning har benyttet.
Apparatet i den Form, hvori det her er kommen til
Anvendelse, findes sammenstillet i Figur 3.
A er 2 meel Natronkalk fyldte uformige Rør, B
indeholder Barytvand. C er en Erlenmeyers Kolbe paa circa
0.5 Litre, der gjennem et ved Bunden udmundende Rør
communicerer med B. medens et lige under
Kautschuk-proppen udmundende sætter den i Forbindelse med
Kjøle-leren D, hvis indre Del efter Classen bestaar af et 27—
3()mm vidt Glasrør, hvortil i øvre og nedre Ende er loddet
Ror med respective 15 og lmm Diameter. Forlaget E er
fuldstændig af samme Construction som det af Jacobsen
benyttede og er oventil forsynet med det af P. Wagner3
foreslaaede med Glaskugler fyldte Rør F.
Ved a, hvor der tindes en indsnevring, er anbragt
en noget større Glaskugle, som temmelig nøie dækker over
det nederste snevre Rør. Idet det til Opsamling af
Kulsyren anvendt^ titrerede Barytvand heldes ned gjennem F,
fjernes Proppen b, indtil det Meste af Barytvandet har
passeret a, men sættes derpaa hurtigt i, saaledes at der
over de nederste Glaskugler bliver staaende noget
Barytvand til en Høide af omtrent 50mm over a. Dersom nu
series of observations instituted by Dr. Jacobsen and J. Y.
Buchanan cannot however be wholly rejected, since the
protracted boiling characteristic of the method they adopted
may possibly have driven off all the carbonic acid contained
in the carbonates, in which case their figures would acquire
importance as expressive of the total amount of carbonic
acid present in the sea-water examined.
Unfortunately, divers untoward circumstances conspired
to prevent my terminating in the winter of 1877—78 the
series of experiments I had begun with the object of
elucidating this intricate subject; my time-, for instance, came
to be unexpectedly occupied in other ways, and during the
greater part of that period I suffered from ill-health. My
observations, therefore, not having progressed so favourably
as I at first had reason to anticipate, I was again obliged
to set out on the Expedition, in 1878, without having
fixed on any reliable method for determining the carbonic
acid present in sea-water. On my return however to
Christiania in the autumn of that year, I recommenced the said
experiments, and succeeded in bringing them to a
satisfactory termination.
A paper by C. Borchers, which had just appeared,1
on the determination of carbonic acid in mineral water,
drew my attention to the apparatus — of which I have
since made frequent use — devised by Alex. Classen2 for
determining carbonic acid in carbonates.
Figure 3 represents • this apparatus as constructed for
my experiments.
A 2 glass tubes, resembling in form the letter V,
filled with soda-lime; B a vessel for baryta water; C an
•Erlenmeyer fiat-bottomed matrass, containing about 0.5
litre, which by means of a tube terminating at the bottom
is made to communicate with B. a similar tube, issuing
immediately beneath the Caoutschouc stopper, putting it
likewise in communication with the cooler D, the inner
portion of which, according to Classen, should consist of a
glass tube from 27mm to 30""" in diameter, with tubes,
measuring respectively 15mm and 7 m-m in diameter, sealed
to its upper and lower extremities. The receiver E has.
precisely the same form as that adopted by Jacobsen, and
is furnished above with a glass tube, F, filled with glass
balls, as suggested by P. Wagner.3
At the point a, where the tube suddenly narrows, is
introduced a somewhat larger glass ball, to fill up, as near
as may be. the opening of the lower or slender portion of
the tube. When the titrated baryta water, which absorbs
the carbonic acid, is being poured down through F, the
stopper b has to be taken out, but must be quickly replaced,
before the whole of the fluid has passed a, in order
that the glass balls to a height of about 50mm above a
1 Journ. fiir pract. Chem. 125 — 353.
2 Fresenius Zeitschrift 15 — 288.
3 Fresenius Zeitschrift 9 — 445,
1 Journ. fiir pract. Chem. 125, p. 353.
2 Fresenius Zeitschrift 15, p. 288.
3 Fresenius Zeitschrift 9, p’. 445.
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