28 



Dette syntes ogsaa meget vanskeligt at forklare, saa- 

 fremt det virkelig skulde forholde sig som af Enkelte paa- 

 staaet. at der i Søvandet skulde rindes et meget stort 

 Overskud af fri Kulsyre ved Siden af en meget Ilden 

 Qvantitet af sure Carbonater. Det maatte aabenbart synes 

 meget rimeligere at forklare de af Dr. Jacobsen gjorte 

 Observationer derved, at Søvandet under den langvarige 

 Kogning ved en eller anden chemisk-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 : 



2U0 CO. Søvand (af sp. Vægt 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- 

 oplosning, hvoraf 1" CC. svarede til 4.<>2o4 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 ubetydeligt Spor af Kulsyre erholdtes. 

 Sluttelig tilsattes circa 0.5 Gr. fuldkommen ren iriskt ud- 

 glødet Soda, hvorpaa det Hele atter fortyndedes med kul- 

 syrefrit Vand til Søvandets oprindelige Volum og saa af- 

 destilleredes i en kulsyrefri Luftstrøm. 



Alleuede fra det Øieblik af, da Yædsken var kommen 

 i Kog, begyndte strax en saa voldsom Kulsyreudvikling. at 

 det i Forlaget anbragte Barytvand slåp store Mængder 

 uabsorberede igjennem, og det viste sig efter endt Opera- 

 tiiin. at kun 1.3 CC. Barytvand var forblevet uneutralise- 

 ret. Heraf beregnes den absorberede Del af den undvegne 

 Kulsyre til 95.3 Mgr.. medens desfonulen meget betydelige 

 Mængder gik igjennem, idet nemlig Barytvandet i et ufor- 

 migt Rør, 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. hvofimod der ved et Forsøg 

 med rint 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 Sovandet forhaandenværende 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 forfellede. Hvad 

 angaar de for Publicationen af Dr. Jacobsens Afhandling 

 i mi Luften i Sovandet udforte Kulsyrebestemmelser, da er 

 det en Selvfolge, at de alle uden Undtagelse maatte røre 

 i enhver Henseende fuldstændig værdilose. idet der ved 

 dém intetsteds er kommen til Anvendelse en Aidestillation 

 til Tørhed eller en saa ridtdreven Concentration, at man 



This fact would obviously be most difficult of expla- 

 nation if, as some have aftirmed, sea-water does actually 

 contain a very large surplus of free carbonic acid alohg 

 with an e-xceedingly small proportion of bicarbonates. A 

 more plausible hypothesis by which to explain Dr. Jacobsen's 

 observations were surely the assumption. that during the 

 protracted process of boiling some of the neutral carbon- 

 ates present in sea-water had been decomposed. 



With the object of ascertainmg 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 compared with distilled water of the 

 same temperature) were distilled almost to dryness in a 

 current of air free from carbonic acid. and the carbonic 

 acid collected in 25™ of baryta water, 1" of which re- 

 presented 4.0204 fflar carbonic acid. On being retitrated 

 with oxalic acid 19.97 w of the baryta water were found not 

 to be saturated, and 20.2"'»'' carbonic acid had accord- 

 ingly been driven off. Water freshly boiled was now pourecl 

 on the residue, and then evaporated, the result yielding a 

 slight trace of carbonic acid; tinally, about 0.5 ""^ puriried 

 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 M 

 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 TJ) conriected with the receiver, being surcharged 

 with the gas. 



At Professor Waages 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 rinely 

 pulverised marble gave no positive result. 



The importance of these observations was not to be 

 questioned, affording 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 ])resence of air 

 in sea-water, such must' as a matter of course be wholly 

 worthless, the metbod 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 



