43 



velser [ritet med Bestemthed kan slutte om Carbonaternes 

 CÆængde i de store Verdenshave. Det synes dog, som om 

 de åf Buchanan adførte Bestemmelser af Kulsyren i At- 

 lanterhavet, (hvorved han inddamper etter forudgaaende Til- 

 sætning af Ohlorbarium og tilslut med stærk Saltsyre for- 

 gjæves har bestræbt sit; for at paavise Kulsyre i Residuet), 

 med Sikkerhed skulde fastsætte en øvre Grændse for den 

 tilstedeværende Carbonatmængde, men dette er i Virkelig- 

 heden ikke Tilfælde. 



Som bejtjendt beskytter uopløselige Sulfater Carbona- 

 ter mod Decomposition endog, naar til Uddrjvelse af Kul- 

 syren anvendes saa radicale Midler som conceutreret Svovl- 

 svre. saaledes at man endog af den Grund har fundet det 

 fornødent at moditicere den af Fresenius og Will angivne 

 Methode til Bestemmelse af Kulsyren i neutrale Carhonater. 1 

 De af Buchanan foretagne Undersøgelser 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. 



Foråt faa Rede paa. hvorvidt en ved Kogning bevir- 

 ket Decomposition af • de i Søvandet indeholdte neutrale 

 Carbonater foregaar i større Udstrækning ogsaa. naar der 

 i Vædsken tindes uopløselige Sulfater, har jeg udfort nogle 

 Forsøg efter den af Buchanan foreslaaede Fremgangsmaade. 

 Af nogle. Vandprøver, som. udersøgte efter den af mig be- 

 nyttede Methode. viste sig at indeholde en Sum af surt- 

 og neutralbunden Kulsyre af 9(3 Mgr. pr. Litre og der- 

 over, erholdtes ved Inddampning til Tørhed efter Tilsæt- 

 ning af Chlorbarium uddrevet kun henimod 50 Mgr., 

 ved en enkelt Vndtagelse erholdtes engang over 50 Mgr. 

 pr. Litre. Det vil sige. den uddrevne Kulsyremæugde var 

 ikke synderlig hoiere end den af Buchanan for Våndet i 

 Æqtatoregnene angivne og beløb sig til kun faa Mgr. over, 

 hvad den surtbundne Kulsyre efter paalidelige Observa- 

 tioner skulde helobe sig til. de endnu i Residuet tilbage- 

 værende Carbonater rykkedes det heller ikke mig at paavise. 



Spørgsmaalet om Carbonaternes Mængde i de sydlige 

 Have maa derfor endnu betragtes som aabent. 



Forhaabentlig resterer endnu en Del af de fra Ckal- 

 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 oversåt paa Tysk. ankom hertil 2det 

 og 3die Hefte for 1879 af Fresenius' Zeitschrift fur anal. 

 Chem.. hvori E. Boklig offentliggjør en Afhandling, 2 hvoraf 

 det sees. at han ved Arbeide med naturlige Mineralvande 

 har observeret Omsætninger mellem kulsur Kalk os svovl- 



1 Fresenius, Qvant. Analyse, ">te Aufl. 36,4 bb. 



2 Fresenius' Zeitschrift, 18 — 195. 



of lime. From what has been already explained, it is ob- 

 vious that uothing definite can be inferred trom earlier 

 statements respecting the proportion of carbonates in the 

 water of the great oceans. The carbonic acid determina- 

 tions performed by Buchanan with water Ironi the Atlantic 

 Ocean (he had recourse to evaporation, adding first chloride 

 of barium, and then attempting, unsuccessfully, to de'tect 

 carbonic acid in the residue by means of strong hydro- 

 chloric acid) would appear to tix a limit for the maximum 

 amount of carbonates contained in sea-water; bul 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 

 vere present in that fluid. I made a few experiments by 

 Buchanaris process. From several samples of sea-water 

 which, examined by the. method 1 adopted, wer.e found to 

 contain 90'"''' of carbonic acid per litre. I succeeded. by 

 evaporation to dryness, after adding a solution of chloride 

 of barium, in liberating about 50'""' only, with a solitary 

 exception, when the amount exceeded 50 m " r 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 hut 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. I 

 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 fiir anal. Chemie for 

 1879 came to hand. in which 'E. Bohlig has published a 

 papér 2 on transformations. observed by him in mineral 

 waters, resulting from the reciprocal action of carbonate of 



1 Fresenius. Qvant. Analyse, ."'te Aufl. 304, bb. 



2 Fresenius' Zeitschrift, 18, p. 195. 



(i* 



