Om Søvandets faste Bestanddele. 



Den temmelig rige Literatur, der handler om Søvands- 

 undersøgelser. gaar helt tilbage til Slutningen af det 

 forrige Aarhundrede. De Kemikere. der fra Begyndelsen 

 af tog dette -Emne under Behandling, lagde naturligvis forst 

 og fremst Yægten paa at bestemme Våndets samlede Salt- 

 mængde eller dets tilsvarende Egenvægt i de forskjellige 

 Dele af Oceanet. 



De første Undersøgelser i denne Retning forte snart 

 til den Slutning, at Havets Saltholdighed ikke var under- 

 kastet andre Forandringer, som ved Datidens analytiske 

 Midler kunde paavises. end slige. der var en nødvendig 

 Følge af særegne forud bekjendte Naturforhold, f. Ex. For- 

 tyndningen i de polare Egne ved store Ismassers Smeltning. 

 Denne Havets Ensartethed med Hensyn til dets samlede 

 Saltgehalt saudsynliggjorde naturligvis ogsaa den Antagelse, 

 at Forholdet mellem dets enkelte Bestanddele var af en 

 lignende uforanderlig Beskaffenhed. Skjønt de første For- 

 søg paa at bestemme Søsaltets Sammensætning ikke førte 

 til saadanne Resultater, der fra Kemiens nuværende Stand- 

 punkt vilde betegnes som overensstemmende, ser vi dog. at 

 allerede Marcet (Phil., trans. 1822) drager den Slutning af 

 sine Søvaudsundersøgelser, at der kun er meget liden Ya- 

 riation i Forholdet mellem Kalk. Magnesia. Klor og Svovl- 

 syre i Hav våndet. At Havet er en ensartet Blanding, eller 

 at Variationerne i dets Sammensætning kun kan dreie sig 

 om smaa Størrelser, er senere bekræftet ved talrige Under- 

 søgelser, men den største Del af de Analyser, der ere ud- 

 førte i denne Retning, ere dog -- lige indtil den Tid. da 

 Forchhammer offentliggjorde sin Afliandling om Søvandet 

 — temmelig værdiløse. da de ialmindelighed er hehæftede ' 

 med altfor store Feil til at kunne have nogen Betydning 

 fra et nyere Standpunkt betragtet. De talrige og fortrin- 

 lige Undersøgelser. Forchhammer har udført for at komme 

 til Klarhed i denne Sag viser tydelig, at man skal arbeide 

 med stor Omhyggelighed, li vis ikke Feilene ved Analysen 

 skal blive storre end de sman Yariationer i Havets Sam- 

 mensætning. Denne udmærkede Forsker har undersøgt 

 180 Yandprover fra de forskjellige Dele' af Yerdenshavet 

 og udført sine Analyser med en Grundighed og Nøiagtig- 



Den norske Nordhavsexpedition. Schmelck: Cliemi. 



On the Solid Matter in Sea-Water. 



T 



he tirst of the numerous works on ocean-water date from 

 the close of the last Century ; and the branch of the 

 subject which. to the earlier authors. would appear of para- 

 mount importance. was naturally the determination of the 

 total amount of salt in sea-water. or the equivalent specitic 

 gravity of the latter, in all parts of the globe. 



( hi instituting observations with this object iu view. 

 it soon became apparent — to the extent at least for which 

 the limited means of analysis then known sufticed — that 

 the proportion of salt in ocean-water was not subjected to ' 

 other disturbing influences than such as could be readily 

 traced to physical causes: for instance, dilution. in the 

 Arctic regions, from the melting of enormous masses of 

 ice. And the remarkable uniformity pre va iling in the pro- 

 portion of the total amount of salt. was plainly in favour 

 of the hypothesis. that a like unvarying relation should 

 subsist between the different constituents. The first expei - - 

 iments to determine the nature of sea-water, did not indeed 

 give results that would now be held to exhibit close 

 agreement: and yet Marcet (Phil. trans. 1822) was led to 

 infer. that the variation in sea-water between lime. mag- 

 nesia, chlorine. and sulphuric acid is relatively very trifling. 

 That the ocean, so to speak. is a homogeneous fluid, or. 

 that the variations exhibited in its composition represent 

 magnitudes comparatively minute. — this view has since 

 been repeatedly confirmed; but the greater part by far of 

 tlie analyses performed to test it — previous to the date 

 at which Forchhammer published his treatise on ocean- 

 water — are of very questionable valne, being most of them 

 beset with errors. which, when viewed in the light of mod- 

 em science, must be regarded as far too considerable to 

 admit of our attaching any real importance to their results. 

 The series of numerous and most successful experiments 

 instituted by Forchhammer. sufhciently attest the care that 

 is needed to keep the errors of analysis from exceedmg 

 in magnitude the inconsiderable variations occurring in the 

 composition of sea-water. That distinguished observer 

 examined no less than 180 samples of sea-water. collected 



i 



