I Aaret 1869 udgik fra England Porcupineexpeditio- 

 iien. hvor der for tørste Gang foruden de øvrige vjdenska- 

 belige Arbeider ogsaa foresloges udført mere omfattende 

 chemiske Undersøgelser. Man besluttede her at benytte 

 den udmærkede Anledning til ved talrige Forsøg saavel 

 med Overfladevand som Vand fra større Dyb at skaffe sig 

 Oplysning om de Fluctuationer, som optræde saavel i de 

 absolute som relative Mængder af de i Søvandet opløste' 

 Gasarter. .Foråt undgaa de Feil. som nødvendigvis maatte 

 indsnige sig. naar de til Gasanalyser bestemte Vahdprøver 

 opbevaredes i længere -Tid før Undersøgelsen, bestemte man 

 sig her for den Udvei at foretage Gasanalyserne ombord. 

 Til ( )|it;igelse af de fra større Dyb stammende Vandprøver 

 benyttedes en meget simpel Vandhenter bestaaende af en 

 hul Metalcylinder med letbevægelige opadslaaende Kegle-' 

 ventiler, et Apparat, hvis Paalidelighed senere Undersøgelser 

 giver Anledning til at betvjvle. Udkogningen og Opsam- 

 lingen af Gasarterne foretoges i alt Yæsentligt som ved de 

 tidligere beskrevne Forsøg, og anvendtes under Analysen til 

 Absorbtion af Kulsyre og Surstof Kalihydrat og pyrogal- 

 lussur Kali. Det siger sig selv. at de paa denne Maade 

 erholdte Resultater maatte være beheftede med meget be- 

 tydelige < >bservationsfeil, livad der ogsaa tydeligst vises af 

 de store Afvigelser mellem de af forskjellige Observatører 

 efter denne Frenigangsmaade udforte Bestemmelser. Som 

 Udtryk for Sammensætningen af den af Overfladevandel 

 udkogte Luft fandt nemlig de tre Chemikere. som paa de 

 tre Togter. hvori denne Expedition deltes, efter hinanden 

 udforte de chemiske Arbeider, følgende Tal: 1 



W". L. Carpenter . 



Hunter 



P. Herbert Carpenter 



31.6 o/ mod 68.4 "/,, N. 



36.4 - -' 63.6 - N. 



30.5 - O - 69.5 - N. 



Dette er kun de af de enkelte ( >bservationer' udle- 

 dede Middelværdier, men. som man ser. er allerede Afvi- 

 gelserne mellem disse overmaade store, medens de enkelte 

 Bestemmelser, som ikke tindes opførte, varierer mellem 

 langt videre Grændser. Saaledes opføres som Ydergrænd; 

 ser for Variationerne af Surstofmængden i Overfladevandet 

 Maximum 45.3 og Minimum 14.0 °/„ al' den samlede (Jasr 

 mængde, Kulsyren iberegnet. 



Porcupineexpeditionens Chemikere ansaa selv sine Re- ' 

 sulfater upaalidelige. dog mindre paa (I rund af Mangler 

 miI Arbeidsmethoderne, end fordi den af dem benyttede 

 Vandbenter tillod Undvigélsen af den Luft. som de mente 

 kunde udvikle sig, naar Våndet fra de størje Dyb naaede 

 np til det veil Overfladen herskende mindre Tryk. De tog 

 forresten sin Tilflugt ogsaa til andre Midler lor at forklare 



In the year 1869, the -Porcupine' Expedition ^Yas 

 dispatched by the British Government, and it was now pro- 

 posed, for the first time, to institute a series of chemical ex- 

 periments on a more comprehensive .scale than any hitherto 

 performed. By taking advantage of tbis excellent øppor- 

 tunity to examine numerous samples of sea-water. both 

 from the surface and from great depths, the fluctuations 

 that occur alike in the absolute and the relative amøimts 

 of gaseous bodies in ocean -water might be effectively 

 investigated, In order to guard against the error that 

 must necessarily arise when the samples of water are pre- 

 served" lov any length of time previous to examination, it 

 was resolvcd to undertake all analyses of- gas on board. 

 For obtaining samples of water from great depths. a very 

 simple instrument was used, consisting of a hollow metal 

 cylinder, furnished witb conical-shaped valves, openingabove, 

 an apparatus the trustworthiness of which subsequent ex- 

 periments have shown reason to doubt. The gas was boiled 

 out and collected . by a process essentially similar to that 

 adopted fm- the experiments previously described. the car- 

 bonic acid and the oxygen having been absorbed by hyd- 

 rate of potash and pyrogallic acid. .As a matter of course, 

 vei7 considerable .érrors of observation would attach to 

 fesults obtained by tbis method, the best proof of which 

 hes in the extent to which the déterminations of different 

 Observers performed by tbis mode of operation are found 

 to vary. For instance, the three cheinists who successivcl\ 

 accompanied the Expedition on the three voyages into which 

 it was divided. express the composition of the air boiled 

 out of surface-water by the following tigures: 1 - 



These amounts. however, are the mean values deduced 

 from the several observations. and yet they vary exceed- 

 ingly; the individual déterminations, which are not given, 

 must obviously have ranged between far w i der limits. Tims. 

 the extreme limits between which the amount of oxygen 

 was found to vary in surfnce-water. is stated to have been 

 45.3 (maximum) and 14.0 (minimum) per cent of the total. 

 amount of gas. inchuling the carbonic acid. 



■ The chemists- who accompained the 'Porcupine' Ex- 

 pedition did not' even themselves regard the fesults obtained 

 as trustworthy, less however on the ground of possible 

 defects in the modes of operation, than because the the ap- 

 paratus used for collecting the water ailmits of the escape 

 of air which, in their opinion, may be liberated on water 

 drawn from great depths reaching the surface, where the atmos- 



Proc. Roy. Soc. Is 



397. 



1 Proc. Roy. Soc. i^s, p. ::i»7 



