5 
de observerede store Afvigelser. saaledes tilskreves stærke 
Bevægelser af Havoverfladen enten ved Storme eller paa 
anden Maade den Evne at forøge Surstofmængden og for- 
ringe Kidsyremængden, ligesom rigt Dyreliv ogsaa tilskre- 
ves en meget stor Indflydelse paa Sammensetningen af den 
i Søvandet opløste Luft. 
I 1871 udgik atter igjen denne Gang fra Tyskland 
en Expedition til Untjersøgelse af Østersøen, hvormed som 
Chemiker fulgte Dr. O. Jacobsen. Med Resultaterne af 
de fra de tidligere Expeditions hidrøremde Gasbestemmelser 
for Øie besluttede ban sig hverken for den ene eller den 
anden af de ved Bonite eller Porcupineexpeditionen anvendte 
Fremgangsmaader men slog ind paa en Middelvei, den eneste, 
som i dette Tilfælde kunde føre til paalidelige Resultater. 
Han delte Undersøgelserne i to Dele og udførte den 
uopsættelige Del af dem nemlig Gasarternes Udkogning 
strax, medens lian. indseende Umuligheden af at udføre til- 
fredsstillende Gasanalyser ombord paa et Fartøi i aaben 
Sø, opsatte deres nærmere Undersøgelse til Hjemkomsten. 
Désværre gav Mangelen af en til Optagelse af Dybvancls- 
prøver egnet paalidelig Vandhenter Anledning til. at det 
Iste A ars Ud bytte af denne Expedition for Gasanalysernes 
Vedkommende reducerede sig til blot og bart Indsamling af 
den Erfaring, som senere skulde komme til Anvendelse ved 
det Aaret efter foretagne Togt i Nordsøen. Manglerne 
ved den paa Porcupineexpeditionen benyttede Vandhenter 
kavde nemlig bevæget Jacobsen til ogsaa til Øsning af de 
for Gasanalyser bestemte Vandprøver at benytte en Vand- 
benter, der nedsænkedes, fyldt med Luft. Naar nu Appa- 
ratet i Dybet aabnedes, absorberedes under det der her- 
skende store Tryk momentant en Del af den nedbragte 
atmosphæriske Luft, hvorved de paa disse Vandprøver ud- 
førte Gasanalyser bleve saa upaalidelige, at der ikke en- 
gang værdigedes dem en Offentliggjørelse. 
De paa Østersøtogtet i 1871 indhøstede Erfaringer, 
muliggjorde det imidlertid for Jacobsen ved en omhyggelig 
Forberedelse til den i 1872 foretagne Expedition i Nord- 
søeu at overvinde eller omgaa de Vanskeligheder. som havde 
bevirket Manglerne ved de paa Porcupineexpeditionen fore- 
tagne Undersøgelser, og det lykkecles ham denne Gang som 
Resultat af sine Arbeider at offentliggjøre en Afhandling. 1 
som giver en Række af vore Tiders Fordringer strengt til- 
fredsstillende Oplysninger om Luften i Søvandet. Til Op- 
tagelse af de til Gasanalyser bestemte Vandprøver fra Dy- 
bet tjente paa IS’ ordsøtogtet et af Dr. H. A. Meyer angivet 
Apparat 2 * * * bestaaende af en tung Metalcylinder, som ved 
Udløsning i det bestemte Dyb faldt ned over to vel islebne 
koniske Ventiler, og derved afspærrede det mellem disse 
1 Ann. Chem. Pharm. 1UT — 1: Jahresbericht der Commission zur 
wissenschaftlichen Untersuchung der deutschen Meere in Kiel, 1*72 
—7.1 — 43. 
Jahresbericht der Commission zur wissenschaftlichen Untorsueh- 
ung der deutschen Meere in Kiel 1H72 — 73 — 5. 
pheric pressure is less. But they had recourse to other 
means whereby to explain the great differences observed, 
ascribing to the state of violent agitation into which the 
surface of the ocean is thrown bv heavy storms, or to some 
other adequate cause, the ability of increasing the proportion 
of oxygen and diminishing that of carbonic acid : an abund- 
ance of animal life, too, was believed to exert very great 
influence on the composition of the air absorbed in sea-water. 
In 1871, an Expedition >vas despatched from Germany 
for the investigation of the Baltic, Dr. (). Jacobsen accom- 
panying it as chemist. Warned by the unsatisfactory 
results of former gas-analyses, he resolved to adopt neither 
of the methods resorted to on the. ‘Bonite’ and ‘Porcupine’ 
Expeditions, but rather to take a middle course, which 
indeed held out the only prospect of success. 
Accordingly, he divided his observations. Experiments 
admitting of- no delay, such as boiling off the gas, were 
performed at once, whereas all analyses of gas, impossible 
as it is found to operate satisfactorily on board a. vessel 
in the open sea, were deferred till his return home. Un- 
fortunately, the want of a trustworthy apparatus for col- 
lecting samples of water from great depths, confined the 
results obtained on the first voyage of the Expedition, 
as regards analyses of gas, to the mere acquisition of 
experience, which, however, there was ample oppor- 
tunity of applying on the cruise undertaken the following 
year in the North Sea. The defective construction of the 
instrument employed for collecting water on the ‘Porcu- 
pine’ Expedition had induced Jacobsen to make use of an 
apparatus which, even when drawing water for gas-anal- 
yses, was sunk full of air. Now, on opening this appa- 
ratus at the required depth, some portion of the air it 
contains will, by reason of the great pressure, be momen- 
tarily absorbed; and hence all analyses of gas with such 
samples of water proved to that extent defective as to be 
not even deemed worthy of publication. 
Meanwhile, taking advantage of the experience ac- 
quired in 1871 on the cruise in the Baltic, Dr. Jacobsen 
succeeded, after careful preparation to meet the require- 
ments of the Expedition undertaken in 1872 to the North 
Sea, in surmounting or evading the difficulties experienced 
on the ‘Porcupine’ Expedition, and was enabled, as the result 
of his labours, to publish a treatise* on the air present in sea- 
water recording a series of eminently satisfactory results. 
For collecting samples of water wherewith to undertake anal- 
yses of gas in water from the bottom, or from great depths, 
an apparatus, described by Dr. H. A. Meyer, was made use 
of on the cruise in the North Sea. 8 It consists of a heavy 
I metal cylinder, which, at the required depth, will drop down 
on two accurately fitted conical valves, cutting off all com- 
1 Ann. Chem. Pharm. 107, p. l ; Jahresbericht der Commission zur 
wissenschaftlichen Untersuchung der deutschen Meere in Kiel, 1^.2 
-7 I 1. 
1 Jahresbericht der CoininisHion zur wissenschaltlichen Untersuch- 
ung der deutschen Meere in Kiel, l s 72 — 73, p. r». 
