43 
velser Intet med Bestémthed kan slutte om Carbonaternes 
Mængde i de store Verdenshave. Det synes dog, som om 
de af Buchanan udførte Bestemmelser af Kulsyren i At- 
lanterhavet, (hvorved han iuddamper efter forudgaaende Til- 
sætning af Chlorbarium og tilslut med stærk Saltsyre for- 
gjæves har bestræbt sig for at paavise Kulsyre i Residuet), 
med Sikkerhed skulde fastsætte en ovre Grændse for den 
tilstedeværende Carbonatmængde, mon dette er i Virkeiig- 
heden ikke Tilfælde. 
Som bekjendt beskytter uopløselige Sulfater Carbona- 
ter mod Decomposition endog, naar til Uddrivelse af Kul- 
syren anvendes saa radicale Midler som concentreret Svovl- 
syre, saaledes at man endog af den Grund har fuudet det 
fornødent at modificere den af Fresen i us og Will angivne 
Methode til Bestemmelse af Kulsyren i neutrale Carbonater. 1 * 
De af Buchanan foretagne 1'ndersøgelser efter Kulsyre i 
Residuet kan derfor ikke betragtes som Bevis for, at den 
ikke skulde have været tilstede, og det fremgaar ogsaa 
tydeligt af hans egne Udtalelser. at han selv har været af 
samme Mening. 
Forat faa Rede paa. hvorvidt en ved Kogniug bevir- 
ket Decomposition af de i Søvandet indeholdte neutrale 
Carbonater foregaar i større Udstrækning ogsaa, naar der 
i Vædsken findes uopløselige Sulfater, har jeg udført nogle 
Forsøg efter den af Buchanan foreslaaede Fremgangsmaade. 
Af nogle V andprøver, som, udersøgte efter den af mig be- . 
nyttede Methode, viste sig at indeholde en Sum af surt- 
og neutralbunden Kulsyre af 96 Mgr. pr. Litre og der- 
over, erholdtes ved Inddampning til Tørhed efter Tilsæt- 
ning af Chlorbarium uddrevet kun henimod 50 Mgr., 
ved en enkelt Undtagelse erholdtes engang over 50 Mgr.' 
pr. Litre. Det vil sige, den uddrevne Kulsyremængde var j 
ikke synderlig høiere end den af Buchanan for Våndet i 
Æqvatoregnene angivne og beløb sig til kun faa Mgr. over, 
livad den surtbundne Kulsyre efter paalidelige Observa- 
tioner skulde beløbe sig til, de endnu i Residuet tilbage- 
værende Carbonater lykkedes det heller ikke mig at paavise. 
Spørgsmaalet om Carbonaternes Mængde i de sydlige 
Have maa derfor endnu betragtes som a a bent. 
Forhaabentlig resterer endnu en Del af de fra Chal- 
lengerexpeditionens Togter hjembragte Vandprøver, og man 
vil i saa Fald ved Undersøgelse af disse kunne give Bi- 
drag til Besvarelsen af disse Spørgsmaal. 
Etterat Ovenstaaende var nedskrevet paa Norsk, men 
førend det endnu var oversat paa Tysk, ankom hertil 2det 
og 3die Hefte for 1879 af Fresenius’ Zeitschrift fur anal. 
Chem.. hvori E. Bohlig offentliggjør en Afhandling, 8 hvoraf 
det sees, at han ved Arbeide med naturlige Mineralvande 
har observeret Omsætninger mel lem kulsur Kalk og svovl- 
of lime. From what has been already explained, it is ob- 
vious that nothing definite can be inferred from earlier 
statements respecting the proportion of carbonates in the 
water of the great oceans. The carbonic acid determina- 
tions performed by Buchanan with water from the Atlantic 
Ocean (he had recourse to evaporation, adding first chloride 
of barium, and then attempting, unsuccessfully, to detect 
carbonic acid in the residue by means of strong hydro- 
chloric acid) would appear to fix. a limit for the maximum 
amount of carbonates contained in sea-water; but such is 
not really the case. 
The presence of insoluble sulphates serving, as is 
known, to protect carbonates against decomposition, even 
when concentrated sulphuric acid is made use of to expel 
the carbonic acid, it was necessary for this reason alone 
to modify the process devised by Fresenius and Will for 
determining carbonic acid in neutral carbonates. 1 Hence, 
the experiments performed by Buchanan with a view to 
detect carbonic acid in the residue, cannot be regarded as 
affording conclusive proof of its absence; indeed, he himself, 
as appears from his statements, is clearly of the same opinion. 
. 
In order to ascertain whether the decomposition by 
boiling of the neutral carbonates in sea-water also took 
place to a considerable extent when insoluble sulphates 
i were present in that fluid, I made a few experiments by 
Buchanan’s process. From several samples of sea-water 
which, examined by the method 1 adopted, were found to 
contain 90 ro,/l of carbonic acid per litre, l succeeded, by 
evaporation to dryness, after adding a solution of chloride 
of barium, in liberating about only, with a solitary 
exception, when the amount exceeded 50 n,jr per litre. The 
proportion of carbonic acid expelled was accordingly not 
much greater than that determined by Buchanan in water 
from the Equatorial Seas, and but a few millegrammes in 
excess of what the carbonic acid forming bicarbonates, ac- 
cording to trustworthy observations, should have been; of 
the carbonates said to be still present in the residue, 1 
failed to detect any trace. 
• The amount of the carbonates contained in the water 
of- the Southern Seas must, therefore, be still regarded as 
an open question. 
It is to be hoped, that some of the samples of water 
collected on the ‘Challenger’ Expedition still remain, in 
which case their examination will serve to throw further 
light on the subject. * 
After this Memoir had been written in Norwegian, 
but previous to its translation into German, the 2nd and 
3rd Parts of Fresenius' Zeitschrift fill* anal. Chemie lor 
1879 came to hand, in which E. Bohlig’ has published a 
paper 8 on transformations, observed by him in mineral 
waters, resulting from the reciprocal action ol carbonate ot 
(i* 
1 Fresenius. Qvant. Analyse. Me Aufl. 3(i4 1)1). 
a Fresenius' Zeitschrift, IS — 19f>. 
1 Fresenius. Qvant. Analyse, Me Aufl. 3(14. bb. 
• * Fresenius' Zeitschrift, is, p. 10‘>. 
