31 



Naar Søvandet i dette Apparat kogtés med fortyndet 

 Svovlsyre i en kulsyrefri Luftstrøm, undveg Kulsyren' meget 

 hurtigt, idet 15 Minutters Kogning fuldstændig strak til 

 for at bringe al Kulsyre over i Forlaget. Søvandets Sul- 

 fater viste altsaa i alle Fald ikke ved Tilstedeværelsen af 

 fri Syre de af J. Y. Buchanan observerede Egenskaber. 

 Naar den p>aa denne Maade uddrevne Kulsyremængde op- 

 samledes og bestemtes, viste den sig altid at stemme nogen- 

 lunde med, hvad man efter den af Dr. .lacobsen- anvendte 

 Methode kunde erholde uddrevet, idet de optrædende Af- 

 vigelser snart vare positive snart negative men i Regelen 

 ikke storre. end at de for den største Del maatte kunne 

 tilskrives Observationsfeil. Ved den af Buchanan i For- 

 slag bragte Udfældning af Svovlsyren erholdt jeg derimod 

 bestandig betydelig for lave Resultater, hvorom senere. 



For samtidig i en og samme Portion at kunne be- 

 stemme baade den neutrallmndne og den samlede Mængde 

 Kulsyre. anvendte jeg følgende Fremgangsmaade. 



Etterat Apparatet fuldstændig var befriet tor kulsyre- 

 holdig Luft. anbragtes i Forlaget paa den for beskrevne 

 Maade 25 CC. Barytvand, hvoraf hver CC. svarede til 

 4,129 Mgr. Kulsyre. hvoretter der i Kolben C heldtes 

 .'ii'u.7 CC. at det til Undersøgelse bestemte Søvand tillige- 

 med 1U CC. af en Svovlsyre. hvoraf hver CC. svarede -til 

 4.099 Mgr. Kulsyre. Indholdet i Kolben ophededes nu 

 under Gjennemleduing af en meget langsom Luftstrøm til 

 Koghede og holdtes i Kog i nogen Tid. Efter Forløb af 

 henimod 15 Minutter fjernedes atter Varmekilden og Væd- 

 sken afkjøledes. idet Luftstrømmen lidt efter- lidt gaves en 

 noget større Hastigked, hvorved den endnu ikke absorberede 

 Kulsyre meget hurtigt bragtes over i Forlaget. 



Efter endt Operation bragtes de i F værende Glas- 

 kugler tilligemed det ved Rorets Vægge beitende Baryt- 

 vand ned i Forlaget E, bvorpaa det Hele retitreredes med 

 en Oxalsyre, hvoraf hver CC. svarede til 3.976 Mgr. Kul- 

 syre. idet alkoholisk Curcuma tjente som Index. Ligeledes 

 skylledes den ved de indre Vægge af Kjøleren heftende 

 Va-dske ved lidt kulsyrefrit destilleret Vand ned i Kolben, 

 hvori den overskydende Syre neutraliseredes med en Natron- 

 lud, hvoraf hver CC. svarede til 2.928 Mgr. CO,, idet 

 Rosolsyre tjente som Index. 



Som Resultat af disse Titreringer erholdtes den sam- 

 lede Kulsyremængde bestemt til omkring 97 Mgr. og den 

 neutralbundne til gjennemsnitlig henimod 53 Mgr. pr. Litre. 

 De 44 Mgr. Kulsyre. som udgjør Differentsen mellem den 

 samlede Kulsyremængde og den neutralbundne. kan aaben- 

 bart ikke forekomme i Søvandet som fri Gasart. men maa 

 forene sig med de allerede færdigdannede Carbonater under 

 Dannelsen af Bicarbonater, og det viser sig altsaa. at de 

 af Dr. Jacobsen gjorte Observationer meget naturligt lade 

 sig forklare derved, at Søvandet ikke indeholder det mind- 

 ste Spor af fri Kulsyre men hele b'6 Mgr! neiitralbunden 

 og kun omkring 44 Mgr. surtbunden Kulsyre pr. Litre. 



On boiling sea-water along with diluted sulphuric 

 acid. exposed to a current of air free from carbonic acid, 

 in tliis apparatus, carbonic acid escaped very rnpidly. the 

 space of 15 minutes sufficing to collect' the whole of it in 

 the receiver. The sulphates in sea-water — at least when 

 free acids were present — did not, accordingly, exbibit the 

 properties ascribed to theni by J. Y. Buchanan. On col- 

 lecting and determining the carbonic acid driven off by this 

 process, the amount was ' invariably found to agree with 

 th.it which could be liberated by Dr. Jacobsen's method, 

 the differences observed having been sometimes positive and 

 sometimes negative, hut as a rule not greater than would 

 admit of imputing them chiefly to errors of observation. On 

 precipitating the sulphuric acid as suggested by Buchanan. 

 the results obtained were invariably too low; but to this 

 subject I sball afterwards' return. 



In order to determine both the proportion of carbonic 

 acid forming the neutral carbonates and the whole amount 

 of carbonic acid contained in one and the same sample of 

 sea-water. I adopted the following mode of procedure. 



Atter expelling from the apparatus all air in which 

 carbonic acid was present, 25 cc of baryta water were 

 introduced. as previously described, into the receiver. each 

 c.centim. representing 4.129 "" jr carbonic acid; 367.7 f of the 

 sea-water to É be examined were then poured into the mat- 

 rass ( C l. along with 10 a of sulphuric acid, each c.centim. of 

 which represented 4.0.99?"» r carbonic acid. The contents 

 of the matrass were now heated, during exposure to a very 

 slow current of air. up to the boilmg-point. and kept for 

 some time at that temperature. After the lapse of about 

 15 minutes. the source of beat was removed and the fluid 

 cooled, the rapidity of the current of air being slightly 

 increased. causing the carbonic acid not yet absorbed to 

 pass off quicklv into the receiver. 



The operation being terminated. the glass balls in 

 the tube F, along with the baryta water adhering to the 

 walls of the tube. were introduced into tbe receiver E, and 

 the whole of its contents retitrated with oxalic acid. each 

 •c.centim. of which represented 3. 976'"'"' carbonic acid. a 

 solutioh of alcoliolic curcuma serving as the index. The fluid 

 adhering to the walls of the cooler was likewise washed 

 down into the matrass with a little distilled water free from 

 carbonic acid. and the surplus acid neutralised by the ad- 

 dition of soda-lye, each c.centim. of which represented '2.928 m 'J r 

 CO 2, rosolic acid serving as the index. 



As the result of this titration, the total amount of 

 carbonic acid was found to be about 97'"'"' and the pro- 

 portion forming neutral carbonates to average about 5.J ' 

 per litre. Now, the difference, 44'"'"'. cannot occur free 

 as gas. but will unite with the carbonates to form bicar- 

 bonates; and hence Dr. Jacobsens observations could be 

 readily explained on the assumption that sea-water contains 

 no trace even of freé carbonic acid. but as much as 53"''"" 

 j>er litre of carbonic acid forming carbonates and only 

 about 44'"'"' per litre of carbonic acid forming bicar- 

 bonates. 



