Stoffe. Dette er mindre end Halvdelen af, hvad Forch- 

 hammer har fundet som Middeltal for Havets organiske 

 liestanddele. men stemmer ganske godt (iverens med nogle 

 Bestemmelser, der i den senere Tid er udført at' Professor 

 Almen 1 i endel Vandprøver fra Omegnen at' Spidsbergen. 

 Almen anvender hertil den samme Methode som ved Drikke- 

 vand, idet lian tilsætter Sovandét Svovlsyre og ved gjen- 

 tagne Kogninger med Kamæleon oxyderer de organiske 

 Storle. Foråt forhindre den skadelige Virkning af Klor- 

 metallerne fortynder han det Horveien med destilleret Vand. 

 Paa denne Maade tinder han. at 100 Kc. Ishavsvand inde- 

 holder 0.0018—0.0038 (ir. organiske Substantser. Nord- 

 soen. Skagerak og Kattegat skulde etter hans Dndersøgelser 

 indeholde en større Mængde organiske Bestanddele. men 

 dog ikke saameget som det ferske Vand fra Floder oglnd- 

 soer. hvilket viser, at Sovandét ikke fremfor dette er be- 

 gavet med nogen særegen reducerende Evne. Paa mange 

 af de fra Expeditionen medbragte Flasker havde der i 

 Tidens Løb udskilt sig et ubetydeligt fnokket Bundfald af 

 organiske Stoffe, der under Mikroskopet viste sig at inde- 

 holde Diatomeer. Filtratet forholdt sig imidlertid ganske 

 ordinært ligeoverfor- den overmangansure Kali. 



Til Bestemmelsen af Kalk. Magnesia og Svovlsyre i 

 Ha v våndet har jeg betjent mig af de almindelige velbe- 

 kjendte Methoder; men de forberedende Undersøgelser, jeg 

 har gjort foråt forsikre mig om Paalideligheden af disse, 

 har vist mig. at de ikke altid giver saa uøiagtige og over- 

 ensstemmende Resultater, som ere nødvendige for et Ar- 

 beide som det foreliggende, hvis man ikke i enkelte Ret- 

 ninger tager nogle Forsigtighedsregler, der ere altfor løst 

 omtalte i de analytiske Haandbøger. Jeg vil derfor i det 

 følgende gaa lidt nærmere ind paa de Fremgaugsmaader. 

 jeg har brugt foråt erholde de nøiagtigste Bestemmelser. 



Kalk og Magnesia. 



Til disse Bestemmelser afveiedes l / 4 Liter Sovand. 

 Etterat Magnesiaen ved Tilsætning a f omtrent 25 Kc. kon- 

 centreret Saltsyre og derpaa følgende Neutralisation med 

 koncentreret Ammoniakoplosning indtil et ubetydeligt Over- 

 skud var forhindret fra at falde ud, blev Kalken i Kulden 

 bundfældt med et Overskud af oxalsur Ammoniak. Efter 

 en Nats Henstand frafiltreredes Bundfaldet, opløstes i varm 

 Saltsyre og udtældtes atter i Koghede med Ammoniak og 

 nogle Draaber oxalsur Ammoniak. Efter 12 Timers For- 

 lob blev Bundfaldet bragt paa Filtrum og bestemt som 

 Ætskalk. Tilstedeværelsen af Klornatrium har ingen ska- 

 delig Iudtiydelse paa Kalkbestemmelsen. men synes tvert- 

 imod at bidrage til en smuk krystallinsk Udfældning af den 

 oxalsure Kalk. Følgende Kontrolbestemmelser viser Ana- 

 lysernes Paalidelighed : 



1 Svenska låkaresålskapets nya handlingar. Ser. II, del III, 

 Stockholm 1871. 



organic matter. This is less indeed than halt the propor- 

 tion Forchhammer gives as the mean tor the organic ele- 

 ments of ocean-water ; it agrees, however, pretty closely 

 With eertain determinations performed some time since by 

 Professor Almen 1 with samples of sea-water collected in the 

 region of Spitzbergen. Almen resorts to the method adopted 

 foi' drinking-water, mixing sulphuric acid with the water. 

 in which. after repeated boiling with permanganate of pot- 

 ash. the organic matter will be oxidized. To counteract 

 the injurious effect of the chlorides, he dilutes the samples 

 beforehand with distilled water. In this manner he Hnds 

 that lim of Arctic sea-water contain from ii.uiilS'- to 

 0.0038»' of organic matter. According to his observations, 

 the proportion is somewhat greater in the North Sea. the 

 Skagerak, and the Oattegat, though not equal to that in 

 the water of rivers and lakes, which shows that sea-water. 

 compared to the latter, cannot be possessed of any special 

 reductive property. In some of the phials brought home 

 with the Expedition, had formed a thin precipitate of or- 

 ganic matter, which. when viewed under a microscope was 

 found to contain Diatoms. The hltered solution. however, 

 behaved as usual when treated with permanganate of 

 potash. 



For determining the potash. magnesia, and sulphuric 

 acid in ocean-water. I have adopted the ordinary, well- 

 known methods; hut the series of preliminarv experiments 

 which I instituted with a view to test their trustworthiness, 

 has convinced me that they do not always give results suf- 

 ficiently accurate and congruous to warrant their adoption 

 here, unless indeed accompanied by eertain precautions too 

 briefly dismissed in analytical class-books. I shall there- 

 fore in the-context dwell more at large on the several 

 modes of operation by which I have sought to obtain the 

 most accurate determinations. 



Lime and Magnesia. 



For determining these substances, a quarter of a 

 litre of sea-water was first weighed. After guarding against 

 the precipitation of the magnesia, by adding about 25 cc 

 of concentrated hydrochloric acid. and then neutralising 

 with a concentrated solution of ammonia, in slight surplus, 

 the lime was precipitated cold, by means of oxalate of am- 

 monia in excess. Next morning the precipitate was hl- 

 tered off, dissolved in warm hydrochloric acid. and again 

 precipitated, at the boiling point. with ammonia and a few 

 drops of oxalate of ammonia. After 12 hours. the solution 

 was filtered, and the precipitate weighed. as caustic lime. 

 The presence of chloride of sodium has no disturbing effect 

 on the lime-determinations; nav. it appareiitly contrihutes 

 towards the beautiful crystalline precipitation of the oxalate 

 of lime. The following test-determinations vouch for the 

 accuracy of. the analyses: — 



1 Svenska låkaresålskapets nya handlingar. Ser. 11. dél III. 

 Stockholm 1871. 



