41 



von Bibra 1 Intet. 



Robinet og Lefort 2 i det røde Hav Spor, 



Pisani 3 ved Bujuk-Déré i Bosporus 0.1569 Gr. pr. Litre, 



C.-Knauss 4 0.011 Gr. pr. Litre. 



Tborpe og Morton 5 i det irske Hav 0.04754 i L000 Dele 



Vand, 

 Dr. Jacobsen i Nordsøen 0.018—0.028 Gr. pr. Litre. 

 Vierthaler i Adriaterhavet 0.815 Gr. pr. Litre. 

 K. Wibel' i det joniske Hav Intet 

 og Buchanan 8 i de sydlige Have enten Intet eller og meget 



smaa Msengder. 



Saa store Forskjelligheder vilde naturligvis være meget 

 paafaldende, i Fald man kunde anse Resultaterne af disse 

 Observationer for aldeles correcte. bvad der imidlertid ikke 

 er muligt. da alle uden Undtagelse ere udførte efter Me- 

 thoder. som kun for aldeles specielle Sammensætninger af 

 Havvandet kunde føre til nogenlunde rigtige Resultater. 



Ved de tidligere i denne Ailiandling beskrevne For- 

 søg er det godtgjort, at Søvandet (under enhver Omstændig- 

 hed det af Forfatteren undersøgte) red Kogning i kulsyre- 

 fri Luft taber al neutralbunden Kulsyre. og det maa end- 

 videre ved de af v. Bibra og Bucbanan udforte Observa- 

 vationer ansees fuldt bevist, at almindeligt Oceanvand ved 

 Inddampning til Torhed selv i en kulsyreholdig Atmosphære 

 undertiden kan give et fuldstændig kulsvrefrit Residuum. 

 medens det kanske ligesaa ofte ikke vil være Tilfælde. idet 

 der ofte af Buchanan og altid af Jacobsen er fundet Car- 

 bi mater i Residuet. Hvor den neutralbundne Kulsyre un- 

 der Inddampningen bortdrives. vil der til Gjengjæld altid 

 udfældes den æqvivalente Mængde Magnesia, som. naar 

 Residuet henstaar i kulsyreholdig Luft før Bestemmelsen, 

 vil kunne gjenoptage en Del Kulsyre. og det er derfor let 

 forklarligt, at man ved Anvendelse af Inddampning vil 

 kunne erholde meget forskjellige Resultater selv i Søvand 

 af fuldstændic identisk Sammensætiiinn. 



En til Bestemmelse af Carbonaterne hyppig anvendt 

 Methode er den. hvoretter Søvandet koges i ca. 1 Time 

 under stadig Fornyelse af det fordunstede Vand. hvoretter 

 det adskilte Bundfald frafiltreres og veies, saaledes som 

 Vierthaler og tiere har gjort, medens T. E. Thorpe og 

 E. H. Morton af den i Søvandet oprindelig indeholdte 

 Kalkmængde og den i Vædsken efter Frariltration af det 

 ved Kogningen udskilte Bundfald tilbage værende beregner 

 den kulsure Kalks Mængde. 



1 Ann. Chem. Pharm. 77 — 9.0. 



'-' Compt. rend. 62 — 436. 



: Compt. rend. 41 — :i3-_>. 



4 Petersb. lead. Bull. 2 — 203 (1860). 



6 Ann. Chem. Pharm. 158 — 122. 



1 Wien. Aoad. Ber. [2} — 56 — 479. 



7 Ber. Berl. chem. Ges. (i — 1*4. 

 9 Proc. Roy. Soc. '-'4 — 604. 



Den norske Nordhavsexpedition. Tornoe : Chemi. 



\'uii I Sibra : ' aone. 



Robinet and Lefort.- in the Red Sea: traces. 



Pisani, 3 near Bujuk-Déré in the Bosporus: 0.1569« T per litre. 



O. Knaiiss: ' (».()1 1 .'"■ per litre. 



Thorpe and Morton, 5 in the Irish Sea: 0.04754 in 1000 



I Kirts ul' water. 

 Dr. Jacobsen, in the North Sea: 0.018— 0.028»' per litre. 

 Vierthaler." in the Adriatic Sea: »)..') 15"' per litre. 

 F. Wibel. 7 in the Ionian Sea: none. 

 Buchanan.* in the Southern Sens: none at all or traces 



only. 



Differences so considerable would indeed be extraor- 

 dinary. assuming tbe results of the observations to be 

 quite correct ; this, however. is simply impossible, since 

 they were all witbout exception obtained by methods none 

 of which, save for sea-water of a particular composition, 

 can lead to results even approximately reliable. 



By the experiments previously described in this Me- 

 moir. it has been shown that sea-water — at least that 

 examined by the autlior — can, by boiling in an atmosphere 

 free from carbonic acid. be made to part with all of its 

 carbonic acid that is present in carbonates: and moreover, 

 the observations of v. Bibra and Buchanan have furnished 

 conclusive prooi'. that ordinary ocean-water when evaporated 

 to dryness even in a atmosphere containiug carl)onic acid, 

 sometimes gives a residue in which no trace of carbonic 

 acid can be detected, but the' reverse will. perhaps, no 

 less frequently prove to be the case, seeing that Buchanan 

 has often. and Jacobsen always, found carbonates present 

 in the residue. When the neutral carbonates are decom- 

 posed during the process of evaporation, an equivalent pro- 

 portion of magnesia will iuvariably be precipitated. which, 

 on the residue being allowed to stand over previous to 

 determination in an atmosphere coiitaining carbonic acid. 

 may. possibly absorb some carbonic acid; and hence. when 

 •recourse is bad to evaporation, very different results may 

 obviously be obtained even with water identical in com- 

 position. 



A method frequently adopted for determining the 

 proportion of carbonates, is to boil the sea-water forabout 

 an hour, while steadily adding freshwater in place of that 

 evaporated. after which the precipitate is filtered off and 

 weighed, as done by Vierthaler and others; T. E. Thorpe 

 and E. H. Morton calculate the proportien of carbonate 

 of lime by comparing the amount of lime originally present 

 in the water with that contained in the fluid" after filtering 

 off the precipitate. 



1 Ann. Chem. Pharm. 77. p. 90. 



"- Comp. rend. <i'J, p. 4. '.'i. 



8 Comp. cend. 41, p. 532. 



4 Petersb. Acad. Bull. 2. p. 203 (1860). 



6 Ann. Chem. Pharm 158, p. 122. 

 Wien. Acad. Ber. [2] .'.li, p. 479. 



7 Ber. Berl. chem. Ges. 6, p. 1S4. 

 . 8 Proc. Roy. Soc. '-'4. p. 004-. 



