41 
von Bibra 1 Intet. 
Robinet og Lefort 2 i clet rode Hav Spor, 
Pisani 3 ved Bujuk-Déré i Bosporus 0.1569 Gr. pr. Litre, 
C. Knauss 4 0.011 Gr. pr. Litre. 
Thorpe og Morton 5 i det irske Hav 0;04754 i 1000 Dele 
Yand, 
Dr. Jacobsen i Nordsøen 0.018 — 0.028 Gr. pr. Litre. 
Vierthaler 6 i Adriaterhavet 0.315 Gr. pr. Litre, 
F. WibeD i det joniske Hav Intet 
og Buchanan 8 i de sydlige Have enten Intet eller og meget 
smaa Mængder. 
Saa store Forskjellighéder vilde natUrligvis være meget 
paafaldende, i Fald man kunde anse Resultaterne af disse 
Observationer for aldeles correcte, .kvad 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 Afliandling beskrevne For- 
søg er det godtgjort, at Søvandet (under enhver Omstændig- 
hed det af Forfatteren undersøgte) ved Kogning i kulsyre- 
fri Luft taber al neutralbunden Kulsyre, og det mua end- 
videre ved de af v. Bibra og Buchanan udførte Observa- 
vationer ansees fuldt bevist, at almindeligt Oceanvand ved 
Inddampning til Tørhed selv i en kulsyreholdig Atmosphære 
undertiden kan give et fuldstændig kulsyrefrit Residuum, 
medens det kanske ligesaa . ofte ikke vil være Tilfælde, idet 
der ofte af Buchanan og altid af Jacobsen er fundet Car- 
bouater i Residuet. Hvor den neutralbundne Kulsyre un- 
der Inddampningen bortdrives, vil der til Gjengjæld altid 
udfældes (Jen æqvivalente Mængde. Magnesia, som, naar 
Residuet henstaar i kulsyreholdig Luft før Bestemmelsen, 
vil kunne gjeuoptage 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 fuldstændig identisk Sammensætning. 
En til Bestemmelse af Carbonaterne hyppig anvendt 
Methode er den, hvorefter Søvandet koges i ca. 1 Time 
under stadig Fornyelse af det fordunstede Vand, hvorefter 
det udskilte Bundfald frafiltreres og veies, saaledes som 
Viertkaler og Uere har gjort, medens T. E. Thorpe og 
E. H. Morton af den i Søvandet opriudelig indeholdte 
Kalkmængde og den i Va*dsken efter Frafiltration af dot 
ved Kogningen udskilte Bundfald tilbageværende beregner 
den kulsure Kalks Mængde. 
1 Ann. Chem. Pharm. 77 — 90. 
9 Compt. rend. 02 — 430. 
9 Compt. rend. 41 — 032. 
* Petersb. Acad. Bull. 2 — 203 (1800). 
6 Ann. Chem. Pharm. 158 — 122. 
6 Wien. Acad. Ber. [2] — 50 — 479. 
7 Ber. Berl. chem. Ges. 0 — 184. 
s Proc. Roy. Soc. 24 — 604. 
Don norske Nordhavaexpedition. Tornoe: Cliomi. 
Von Bibra: 1 none. 
Robinet and Lefort, 2 in the Red Sea: traces. 
Pisani, 8 near Bujuk-Déré in the Bosporus: 0.1 569^ per litre. 
C. Knauss: 1 0.01 l-' 7r per litre. 
Thorpe and Morton, 6 in the Irish Sea: 0.04754 in 1000 
parts of water. 
Dr. Jacobsen, in the North Sea: 0.018 — 0.028:'' per litre. 
Vierthaler,® in the Adriatic Sea: 0.315'" per litre. 
F. Wibel, 7 in the Ionian Sea: none. 
Buchanan, 3 in the Southern Seas: none at all or traces 
only. 
Differences so considerable would indeed be extraor- 
dinary, assuming the results of the observations to be 
quite correct; tins, however, is simply impossible, since 
they were all without 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 author — 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 proof, that ordinary ooean-water when evaporated 
to dryness even in a atmosphere containing carbonic 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 invariably be precipitated, which, 
on the residue being allowed to stand over previous to 
determination in an atmosphere containing carbonic acid, 
may possibly absorb some carbonic acid; and hence, when 
recourse is had 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 searwater for about 
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 proportion 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, j>. 90. 
* Comp. rend. 62, p. 436. 
3 Comp. rend. 41, p. 532. 
4 Petersb. Acad. Bull. 2, p. 203 (I860). 
6 Ann. Chem. Pharm.. 158, p. 122. 
0 Wien. Acad. Bcr. [2] 56, p. 479. 
7 Bcr. Berl. chem. Gos. 6, p. 184. 
8 Proc. Roy. Soc. 24. p. 604. 
6 
