de observerede sture Afvigelser, saaledes tilskreves stærke 

 Bevægelser af Eavoverfladen' enten ved Storme eller paa 

 anden Maade den Evne at forøge Surstofmængden og for- 

 ringe Kulsyremængden, ligesom rigl Dyreliv ogsaa tilskre- 

 ves en meget stor Indflydelse paa Sammensætningen af den 

 i Sovandet opløste Luft. 



I 1871 udgik atter igjen denne Gang fra Tyskland 

 en Expedition til Ondersøgelse af Østersøen, hvormed sinn 

 Chemiker fulgte Dr. 0. Jacobsen. Med Resultaterne af 

 de fra de tidligere Expeditioner hidrørende Gasbestemmelser 

 for Oie besluttede han sig hverken for den ene eller den 

 anden af devedBonite eller Porcupineexpeditionen anvendte 

 Fremgangsmaader men slog ind paa en Middelvei, den eneste, 

 smii i dette Tilfælde kunde tore til paalidelige Resultater. 



Han delte Unidersøgelserne i to Dele og udibrte den 

 uopsættelige Del af dem nemlig Gasarternes Udkogning 

 strå x. medens han. indseende Dmuligheden af at udfore til- 

 fredsstillende Gasanalyser ombord paa et Fartøi i aabeii 

 So. opsatte deres nærmere Undersøgelse til Hjemkomsten. 

 Desværre gav Mangelen af en til Optagelse af Dybvands- 

 prover egnet paalidelig Vandhenter Anledning til. at det 

 Iste Aars Qdbytte 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 

 havde nemlig bevæget Jacobsen til ogsaa til Øsning af de 

 for Gasanalyser bestemte Vandprøver at benytte en Vand- 

 henter. der nedsænkedes fyldt med Luft. Naar nu Appa- 

 ratet i Dybel aabnédes, absorberedes under det der her- 

 skende store Trvk momentant en Del at- den nedbragte 

 atmosphæriske Luft, hvorved de paa disse Vandprover 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- 

 søen at overvinde eller omgaa de/Vanskeligheder, som bavde 

 bevirket Manglerne ved de paa Porcupineexpeditionen fore- 

 tagne l ndersøgelser, og det lykkedes 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 Sovandet. Til Oj>- 

 tagelse af de til Gasanalyser bestemte Vandprøver fra Dy- 

 bet tjente paa NordsøtogteJ 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 



'' Ann. Chem. Pharm. 167 — 1: Jahresberieht der Commission zur 

 wissenschaftlichen Untersuctauig iler deutschen Bleeré in Kiel, 1872 

 — 7.', — 43. ■ 



- Jahresberieht der Commission zur wissenschaftlichen Untersueh- 

 img der deutschen Meere m Kiel 1872 — 73' — 5. 



pheric pressure is less. But tbey had recourse to other 

 nieans wbereby to explain the great differences observed, 

 ascribing to the state of violent agifation into which the 

 surface bf the ocean is tbrov*n by heavy- storms, or to some 

 other adequate cause, the ability ofincreasing the proportion 

 of oxygen and diminishing that ofcarbonic acid; anabund- 

 auce bf animal lite. too. was beHeved to exert very great 

 inriuence on the composition of the air absorbed in sea-water. 

 In 1871. an Expedition was despatched frpm Germany 

 for the investigation of the Baltic. Dr. O.Jacobsen accom- 

 panying it as chemist. Warnéd by the unsatisfactory 

 results of former gas-analyses, he resolved to adopt ueither 

 of the ihethods 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 bis 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- 

 tarilv absorbed; and hence all analyses of gas with such 

 samples of water proved to that extent defective as to be 

 not even deeriied worthy of publication. 



Me;inwhile. taking advantage of the experience ac- 

 quired in 1871 on the cruise in the Baltic. Dr. Jacobsen 

 succeeded, atter cafeful preparation to meet the require- 

 ments of the Expedition undertaken in 1872 to the North 

 Sea, in surmounting or evading the difticulties experienced 

 on the 'Porcupine' Expedition. and was ehabled, as the result 

 of his labours, to publish atreatise 1 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. 2 It consists of a heavy 

 metal cylinder", which. at the required depth. will drop down 

 on two accurately titted conical valves, cutting ofl' all com- 



1 Ann. Chem. Pharm. 167, p". I; Jahresberieht der Commission zur 



wissenschaftlichen Untersuchung der deutschen Meere in Kiel, 1872 

 — 73, p. 4.">. 



2 Jahresberieht der Commission zur wissenschaftlichen Untersuch- 

 ung der deutschen Meere in Kiel, 1*72 — 73, p. 5. 



