28 
Dette syntes ogsaa meget vanskeligt at forklare, saa- 
fremt det virkelig skulde forholde sig som åf Enkelte paa- 
staaet, at der i Søvandet skulde findes et meget stort 
Overskud af fri Kulsyre ved Siden af en meget liden 
Qvantitet af sure Carbonater. Det maatte aabenbart synes 
meget rimeligere at forklare de at Dr. Jacobsen gjorte 
Observationer derved, at Søvandet under den langvarige 
Kogning ved on eller anden chcmisk Reaction gav Slip paa 
noget af sin neutralt bundne Kulsyre. 
For at komme paa det Rene med, om dette virkelig 
forholdt sig saa, gik jeg frem paa følgende Maade: 
200 CC. Søvand (af sp. Vregt 1.0267 ved 17.°5 C. i 
Forhold til destilleret Vand af samme Temperatur) afdestil- 
leredes næsten til Tørhed i en kulsyrefri Luftstrøm, og op- 
fangedes den undvigende Kulsyre i 25 CC. af en Baryt- 
opløsning, hvoraf 1 CC. svarede til 4.0204 Mgr. Kulsyre. 
Ved Retitration med Oxalsyre viste det sig, at 19.97 CC. 
af det anvendte Barytvand var uneutraliseret. hvoraf den 
undvegne Kulsyre beregnedes til 20.2 Mgr. Residuet paa- 
heldtes nu friskt udkogt Vand, som atter afdestilleredes, 
hvorved endnu et ubctydeligt Spor af Kulsyre erholdtes. 
Sluttelig tilsattes circa 0.5 Gr. fuldkommen ren friskt ud- 
glødet Soda, hvorpaa det Hele atter forty ndedes med kul- 
syrefrit Vand til Søvandets oprindelige Volum og saa al- 
destilleredes i en kulsyrefri Luftstrøm. 
Allerede fra det Øieblik af, daYædskfen var koiiunen 
i Kog, begyndte strax en saa voldsom Kulsyreudvikling, at 
det i Forlaget anbragte Barytvand slap store Mængder 
uabsorberede igjennein, og det viste sig efter endt Opera- 
tion, at kun 1.3* CC. Barytvand var forblevet uneutralise- 
ret. Heraf beregne» den absorberede Del af den undvegne 
Kulsyre til 95.3 Mgr., medens desforuden meget betydelige 
Mængder gik igjennom, idet nemlig Barytvandet i et ufor- 
migt Ror, som var anbragt foran Forlaget, fuldstændigt 
var forbrugt. 
Efter Forslag af Professor Waage gjentoges Forsøget 
med varmt fældt, ved 100° tørret kulsur Kalk. hvoraf det 
ogsaa lykkedes at uddrive ikke ubetydelige om end meget 
mindre Mængder Kulsyre, hvorimod der ved et Forsøg 
med fint pulveriseret Marmor ikke erholdtes noget sikkert 
Resultat. 
Betydningen af disse -Observationer kunde ikke være 
tvivlsom. da det hermed paa det Tydeligste var godtgjort, at 
den i Søvandet forhaaudenværende Saltblanding ved Kog- 
hede decomponerede neutrale Carbonater, og dermed ogsaa, 
at alle de hidindtil gjorte Kulsyrebestemmelser med Hen- 
syn paa sin Hensigt at bestemme den i Søvandet inde- 
holdte frie og surt bundne Kulsyre vare forfeilede. Hvad 
angaar de før Publicationen af Dr. .Jacobsens Afhandling 
om Luften i Søvandet udførte Kulsyrebestemmelser. da er 
det eu Selvfølge, at de alle uden llndtagelse maatte være 
i enhver Henseende fuldstændig værdiløse, idet der ved 
dem intetsteds er kommen til Anvendelse en Afdestillation 
til Tørhed eller en saa vidtdreven Concentration, at man 
This fact would obviously be most difficult ol expla- 
nation ifi as some have affirmed, sea-water does actually 
contain a very large surplus of free carbonic acid along 
with an exceedingly small proportion of bicarbonates. A 
more plausible hypothesis by which to explain Dr. Jacobsens 
observations were surely the assumption, that during the 
protracted process of boiling some ol the neutral carbon- 
ates present in sea- water had been decomposed. 
With the object of ascertaining whether such was 
really the case, I went to work as follows. 
Two hundred c.centim. of sea-water (sp. grav. 1.0267 ? 
temp. 17.°5 C., as computed with distilled water ol the 
same temperature) were distilled almost to dryness in a 
current of air free from oarbonic acid, and the carbonic 
acid collected in 25 cc of baryta, water, 1 IC of which re- 
presented 4.0204'"*"' carbonic acid. On being retitrated 
.with oxalic acid 19.97 M of the baryta water were found not 
to be saturated, and 20.2 w * r carbonic acid had accord- 
ingly befen driven oft. Water freshly boiled was now poured 
on the residue, and then . evaporated, the result yielding a 
slight trace of carbonic acid; finally, about. 0.5 purified 
and freshly heated soda was added, • and the whole com- 
pound again diluted with water, from which all carbonic 
acid had been expelled, to the original volume of the 
sample, and then distilled in a current of air free from 
carbonic acid. 
From the very moment at which the fluid began to 
boil, so rapid was the liberation of carbonic acid that 
large quantities passed unabsorbed through the baryta 
water; and, on the operation being terminated, 1.3 " 
only of the baryta water had not been neutralised. Hence 
the absorbed portion of the carbonic acid was calculated 
at 95.3 exclusive of which a very considerable quantity, 
as before stated, passed off into the atmosphere, the baryta 
water, placed in a glass tube (resembling in form the 
letter U) connected with the receiver, being surcharged 
with the gas. 
At Professor Waage’s suggestion I repeated the ex- 
periment with carbonate of lime, precipitated warm and 
dried at a temperature of 100° C., and succeeded in expel- 
ling carbonic acid in considerable, though not so large, 
quantities as before, whereas an experiment with finely 
pulverised marble gave no positive result. 
The importance of these observations was not to be 
questioned, aft'ording as they did conclusive proof that the 
saline mixture in sea-water, on the temperature being raised 
to the boiling point, decomposed neutral carbonates, and 
likewise that all carbonic acid determinations hitherto at- 
tempted with the object of measuring the carbonic acid 
present in sea-water were faulty. As regards the car- 
bonic acid determinations performed previous to the publi- 
cation of Dr. Jacobsen’s Memoir on the presence of air 
in sea-water, such must as a matter of course be wholly 
worthless, the method of distillation to dryness having in 
no case been adopted, or that of concentrating the fluid 
till further evaporation ceased to expel carbonic acid. The 
