4 
o -f- N pr. 
Litre 
16.0 
I 6.2 
0 -f- iV = i oo 
0°/o 
3**4 
33-2 
N°lo 
68.5 
66.8 
I Aaret 18(59 udgik fra England Porcupineexpeditio- 
nen, livor der for førete Gang foruden de øvrige videnska- 
bolige 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. Forut undgaa de Feil, som nødvendigvis maatte 
indsnige sig, naar de til Gasanalyser bestemte Vandprøver 
opbe våredes i længere Tid før Undersøgelsen, bestemte man 
sig her for den Udvei at foretage Gasanalyserne ombord. 
Til Optagelso af do fra større Dyb stammende Vandprøver 
benyttedes en (meget simpel Vandhcnter bestaaende at en 
bul Metalcylinder med letbevægelige opadslaaende Kegle- 
ventiler, et Apparat, hvis Paalidelighed senere Undersøgelser 
giver Anledning til at bétvivle. Udkogningen og Opsam- 
lingen af Gasarterne forøtoges i alt Væsentligt som ved de 
tidligere beskrevne Forsøg, og anvendtes under Analysen til 
Absorbtion af Ivulsyre og Surstof Kalihydrat og pyrogal- 
lussur Kali. Det siger sig selv, at de paa denne Maade 
erholdto Resultater maatte være beheftede mod meget be- 
tydelige Observationsfeil, livad der , ogsaa tydeligst vises al 
de store AjVigelsør mellom de faf forskjellige Observatører 
efter. denne Fremgangsmaade udførto Bestemmelser. Som 
Udtryk for Sammensætningen af den af Overfladévandet 
udkogte Luft fandt nemlig de tro Ohemikere, som paa de 
tre Togter, hvori denne Expedition deltes, efter hinanden 
udførto cje chemiske Arbeider, tølgende Tal: 1 
W. L. Carpenter . . . . 31.6 °/ 0 0 mod 68.4 °/ 0 N* 
Hunter 36.4 - 0 - 63.6 - N. 
P. Herbert Carpenter . . . 30.5 - 0 69.5 - N. 
Dotte er kun de af de enkelte Observationer udle- 
dede Middelværdier, men, som man ser, er allerede Afvi- 
gelserne melle m disse overmaade store, medens. de enkelte 
Bestemmelser, som ikke tiudes opførte, varierer mcllem 
langt videre Grændser. Saaledes optøres som ^ dergrænd- 
ser for Variationerne af Surstofmængden i Cverfladevandet 
Maximum 45.3 og Minimum 14.0 °/ 0 af den samlede Gas- 
mængde, Kulsyren iberegnet. 
Porcupineexpeditionens Ohemikere ansaa selv sine Re- 
sultater upaalidelige, dog mindre paa (i rund af Mangler 
ved Arbeidsmethoderne, end fordi, den af dem benyttede 
Vandhcnter tilled Undvigelsen af den Luft. som de mente 
kunde udvikle sig. naar Våndet fra* de større Dyb naaede 
op til det ved Overfladen herskende* mindre Tryk. De tog 
forresten sin Tilflugt .ogsaa til andre Midler for at forklare 
1 Proc. Roy. Soe. !>• — 397. 
0 N pr. 
Litre 
16.0 
16.2 
0 -(- N= ioo 
0 p.ct. 
3i-4 
33-2 
N p.ct. 
68.5 
66.8 
In the year 1869, the * Porcupine’ Expedition was 
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 talcing advantage of this excellent oppor- 
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 amounts 
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 for any length of time previous to examination, it 
was resolved to undertake all analyses of gas on board. 
For obtaining samples of water from' great depths, a very 
simple instrument was used, consisting ol a hollow metal 
cylinder, furnished with conical-shaped valves, opening above, 
an apparatus the trustworthiness ol which subsequent ex- 
periments have shown reason to doubt. The gas was boiled 
out and collected by a process essentially similar to that 
adopted for 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 ol course, 
very considerable errors ol observation would attach to 
results obtained by this method, the best proof of which 
lies in the extent to which the determinations of different 
observers performed by this møde of operation are found 
to vary. For instance, the three chemists who successively 
accompanied the Expedition on the three voyages into which 
it was divided, express the composition ol the air boiled 
out of surface-water by the following figures: 1 - 
W. L. Carpenter . . . 31.6 p.ct. 0 and 68.4 p.ct. N. 
Hunter 36.4 - 0 - 63.6 - N. 
P. Herbert Carpenter . 30.5 0 69.5 - N. 
These amounts, however, are the mean values deduced 
from the several observations, and yet they vary exceed- 
ingly: the individual determinations, which are not given, 
must obviously have ranged between far wider limits. Thus, 
the extreme limits between which the amount ol oxygen 
was found to vary in surface-water, is stated to have been 
45.3 (maximum) and 14.0 (minimum) per cent ol the total 
amount of gas, including the carbonic acid. 
The chemists who accompanied the ‘Porcupine’ Ex- 
pedition did not even themselves regard the results obtained 
‘ as trustworthy,’ less however on the ground of possible 
defects in the modes of operation, than because the thé ap- 
paratus used for collecting the water admits of the escape 
of air which, in their opinion, may be liberated on water 
drawn from great depths reaching the surface, where the atmos- 
1 Proc. Roy. Soc. IS, p. 397. 
