40 
ponere neutrale Carbonater maa blive at tilskrive gradvise 
Omsætiiinger mellem de i Søvaudet existerende kulsure 
Salte og Maguesiaforbindelseme. og de ai Dr. Jacobsen 
hos So våndet iagttagne Kgenskaber maa derfor ogsaa i 
mere eller mindre Grad tilligge alle andre magnesiaholdige 
Mineral vånde, eller naar man hegger Roses ovenciterede 
Udtalelser til Grund. alle Saltopløsninger. forsaavidt de 
foruden Alkalier og Jordalkalier tillige indeholder opløse- 
lige Salte ai' nogen af de svagere Baser, som med Kulsyren 
danner ubestandige Forbindelser. Denne Omstændighed 
vil saaledes uden videre stemple saa godt som alle de til 
Bestemmelse af Forholdet mellem den frie og bundne Kul- 
syre j Mineralvande anvendte talrige Metlioder som niere 
og mindre upaalidelige ligeoverfor magnesiaholdige Mine- 
ralvaude, idet man ved dem til Bestemmelse af neutral- 
1, mulen Kulsyre enten anvender Residuet fra Inddampning 
eller paa anden Maade benytter sig af Koguing. hvor den 
efter det forhen udviklede vil være utilladelig. 
Det vil sluttelig ikke være paa urette Sted kortelig 
at berøre de Synsmaader. som fra ældre Tider bar været 
gjort gjældende, livad angaar de i Sovandet indéholdte 
Carbonater. 
Efter de Fremgangsmaader, hvorved disse af ældre 
Forfattere ere bestemte, kunde de naturligvis Sun erholdes 
udskilte i Form af kulsur Kalk eller, som af enkelte ogsaa 
fundet. lidt kulsur Magnesia, men deraf følger ingenlunde, 
at de med Nødvendighed oprindelig skulde forekommet i 
Søvaudet under denne Form. ja dette er saa langt i ra 
sikkert, at jeg meget mere skulde være tilbøielig til at tro, 
at saa ikke er Tiliælde. Koger man nemlig Søvand i det 
af Dr. Jacobsen beskrevne Luftudkogningsapparat, undviger 
der. som allerede før bennerket. meget siuaa Qvantiteter 
Kulsyre. idet man kan fortsætte Kogningen med vexlende 
Afkjøling en hel Time uden at faa uddrevet mere end en 
Brøkdel af Milligram pr. Litre. Kogepuuctet vil her i 
Begyndelsen ligge meget lavt, men stiger, efterhaanden som 
den undvigende Luft og den dannede Yaiuldamp forøger 
Trykket, meget liurtigt. saaledes at jeg allerede under den 
første Halvdel af Operationen bar observeret en Tempera- 
ratur af 89" C. Naar saaledes de i Søvaudet indeholdte 
sure Carbonater vise en saa haardnakket Modstand mod 
Decomposition, at de i en hel Time skulde saa godt som 
aldeles uden Virkning kunne udsættes for en Temperatur 
af omkring 90° C.. da synes mig denne Egenskab at passe 
noget bedre paa surt kulsurt Natron end paa sur kulsur 
Kalk. og det vilde desuden falde vanskeligt at forklare 
Sovandets tydelige alkaliske Reaction, medmindre man kunde 
ajitage. at Carbonaterne i det Mindste for en ikke ringe 
Del bestod af Alkalisalte. 
Med Hensyn paa Qvantiteten af de i Sovandet fore- 
kommende kulsure Salte, da stemme de derover existerende 
Opgaver meget daarligt overens, de lyde i Regelen paa 
Spor undertiden endog paa lutet, medens * der af enkelte 
igjen er opført forholdsvis store Mængder. Saaledes linder 
decomposing when boiled neutral carbonates, arises from 
the slow reciprocal action of the carbonates and salts of 
magnesia it contains, and the properties observed by Dr. 
Jacobsen in sea-water must therefore to a greater or less 
extent distinguish all mineral waters containing magnesia 
compounds, or. according to Rose, in bis statements quoted 
above, all solutions of salts, provided they contain, exclusive 
of sodium, potassium, lime, barium, and strontium, also 
soluble salts of some one of the weaker bases, which 
along with carbonic acid form inconstant combinations. 
Hence, this circumstance clearly shows, that ol the nu- 
merous methods devised for determining, in mineral waters, 
the relative proportion of free carbolic acid and that 
present in carbonates nearly all are, when magnesia is 
present, unreliable, since for the determination of the 
carbonic acid present in carbonates, either the residue from 
evaporation Or'some other result ol boiling is had recourse 
to. which has been shown to be inadmissible. 
Finally, it will not be out of place to notice the views 
originally entertained with regard to the carbonates present 
in sea-water. 
By the process according to which the earlier chem- 
ists determined these compounds, they could of course ob- 
tain them only in the form of carbonate of lime, or. as 
found by some observers, along with a little, carbonate ol 
magnesia; but from this it does not by any means follow 
that they necessarily occur in that form in sea-water ; nay, 
I am myself inclined to believe that such is not the case. 
Oil boiling sea-water in the apparatus described by Dr. 
Jacobsen, very small quantities only of carbonic acid are 
found to escape; the fluid may be alternately boiled and 
cooled for an hour together without liberating more than 
a fraction of a milligramme per litre. The boiling-point 
with this method will at first be very low. hut. on the 
pressure being increased by the escape of the air and the 
formation of steam, rapidly rise; even in the first halt ol 
the operation I have observed a temperature of 89" C. 
The. vigorous resistance to decomposition thus exhibited by 
the bicarbonates in sea-water, which admits of their being 
exposed almost without effect for an hour together to a 
temperature of nearly 90" C., would rather seem to indi- 
cate bicarbonate of soda than bicarbonate of lime; and 
besides, the decided alkaline reaction of sea-water would be 
difficult to explain unless by assuming the carbonates — 
or a considerable portion of them at least — to consist ol 
I carbonate of soda and potash. 
With regard to the proportion of carbonates present 
in sea-water, the results as yet obtained agree but very 
indifferently ; the majority of observers have detected traces 
only or none whatever, whereas some allege to have found 
comparatively large quantities, as will be seen from the 
following Table. 
