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41
von Bibra1 Intet.
Robinet og Lefort2 i det rode Hav Spor.
Pisania ved Bujuk-Déré i Bosporus 0.1569 Gr. pr. Litre,
C.Knauss4 0.011 Gr. pr. Litre,
Thorpe og Morton5 i det irske Hav 0.04754 i 1000 Dele
Vand, .
Dr. Jacobsen i Nordsøen 0.018—0.028 Gr. pr. Litre,
Vierthaier0 i Adriaterhavet 0.315 Gr. pr. Litre,
F. Wibel7 i det joniske Hav Intet
og Buchananö i de sydlige Have enten Intet eller og meget
smaa Mængder.
Saa store Forskjelligheder vilde naturligvis være meget
paafaldende, i Fald man kunde anse Resultaterne af disse
Observationer for aldeles correcte, hvad der imidlertid ikke
er muligt, da alle uden Undtagelse ere udførte efter
Methoder, som kun for aldeles specielle Sammensætninger af
Havvandet kunde føre til nogenlunde rigtige Resultater.
Ved de tidligere i denne Afhandling beskrevne
Forsøg er det godtgjort, at Søvandet (under enhver
Omstændighed det af Forfatteren undersøgte) ved Kogning i
kulsyrefri Luft taber al neutralbunden Kulsyre, og det maa
endvidere ved de af v. Bibra og Buchanan udførte
Observa-vationer ansees fuldt bevist, at almindeligt Oceanvand ved
Inddampning til Tørhed selv i en kulsyreholdig Atmosphære
undertiden kan give et fuldstændig kulsyrefrit Residuum,
medens det kanske ligesaa ofte ikke vil være Tilfælde, idet
der ofte af Buchanan og altid af Jacobsen er fundet
Car-bonater i Residuet. Hvor den neutralbundne Kulsyre
under Inddampningen bortdrives, vil der til Gjengjæld altid
udfældes den æqvivalente Mængde Magnesia, som, naar
Residuet henstaar i kulsyreholdig Luft før Bestemmelsen,
vil kunne gjenoptage en Del Kulsyre, og det er derfor let
forklarligt, at man ved Anvendelse af Inddampning vil
kunne erholde meget forskjellige Resultater selv i Søvand
af fuldstændig identisk Sammensætning.
En til Bestemmelse af Carbonaterne hyppig anvendt
Methode er den, hvorefter Søvandet koges i ca. 1 Time
under stadig Fornyelse af det fordunstede Vand. hvçrefter
det udskilte Bundfald frafiltreres og veies, saaledes som
Vierthaier og flere har gjort, medens T. E. Thorpe og
E. H. Morton af den i Søvandet oprindelig indeholdte
Kalkmængde og den i Vædsken efter Frafiltration af det
ved Kogningen udskilte Bundfald tilbageværende beregner
den kulsure .Kalks Mængde.
Von Bibra:1 none.
Robinet and Lefort,- in the Red Sea: traces.
Pisahi,3 near Bujuk-Déré in the Bosporus: 0.1569"’’per litre.
C. Knaüss:4 0.011> per litre.
Thorpe and Morton,5 in the Irish Sea: 0.04754 in 1000
parts of water.
Dr. Jacobsen, in the North Sea: 0.018—0.028f per litre.
Vierthaier,6 in the Adriatic Sea: 0.3151"" per litre.
F. Wibel.7 in the Ionian Sea: none.
Buchanan,8 in the Southern Seas: hone at all or traces
only.
Differences so considerable would indeed be
extraordinary. assuming the resists of the observations to be
quite correct; this, however, is simply impossible, since
they were all without exception obtained by methods none
of which, save for sea-water of a particular composition,
can lead to results even approximately reliable.
By the experiments previously described in this
Memoir, it has been shown that sea-water — at least that
examined by the author — can, by boiling in au atmosphere
free from carbonic acid, be made to part with all of its
carbonic acid that is present in carbonates; and moreover,
the observations of v. Bibra and Buchanan have furnished
conclusive proof, that ordinary ocean-water when evaporated
to dryness even in a atmosphere containing carbonic acid,
sometimes gives a residue in which no trace of carbonic
acid can be detected, but the’ reverse will, perhaps, no
less frequently prove to be the case, seeing that Buchanan
has often, and Jacobsen always, found carbonates present
in the residue. When the neutral carbonates are
decomposed during the process of evaporation, an equivalent
proportion of magnesia will invariably be precipitated, which,
on the residue being allowed to stand over previous to
determination in an atmosphere containing carbonic acid,
may. possibly absorb some carbonic acid; and hence, when
•recourse is had to evaporation, very different results may
obviously be obtained even with water identical in
composition.
A method frequently adopted for determining the
proportion of carbonates, is to boil the sea-water for about
an hour, while steadily adding freshwater in place of that
evaporated, after which the precipitate is filtered off and
weighed, as clone by Vierthaier and others; T. E. Thorpe
and E. H. Morton calculate the proportion of carbonate
of lime by comparing the amount of lime originally present
in the water with that contained in the fluid’ after filtering
off the precipitate.
1 Ann. Chem. Pharm. 77 — 9,0.
- Compt. rend. 62 — 430.
3 Compt, rend. 41 — 532.
4 Petersb. Acad. Bull. 2 — 203 (I860».
5 Ann. Chem. Pharm. 158 — 122.
6 "Wien. Acad. Ber. [2]. — 56 — 479.
7 Ber. Berl. chem. Ges. 6 — 184.
8 Proc. Roy. S oe. 24 — 604.
Deu norske Nordliavsexpedition. Tornøe: Cliemi.
1 Ann. Chem. Pharm. 77, p. 90.
2 Comp. rend. 62, p. 436.
3 Comp. rend. 41, p. 532.
4 Petersb. Acad. Bull. 2, p. 203 (1860).
s Ann. Chem. Pharm. 158, p. 122.
0 Wien. Acad. Ber. [21 56, p. 479.
7 Ber. Berl. chem. Ges. 6, p. 184.
.8 Proc. Roy. Soc. 24. p. 604.
6
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