94 



HYDROGRAPHY. 



There is hardly any reason to believe that the amount of nitrogen has changed to any appre- 

 ciable degree during the storing, and as the differences found in the amount of nitrogen are between 

 0-14 and 0-60, and thus by far exceed the unavoidable observational errors, there can be no doubt but 

 that the cause of this larger quantity of nitrogen must be due to gases contained in the tubes, before 

 the water got in there. To effect a proper examination of this, the quantity of air in 5 of the remai- 

 ning tubes, which had been pumped out, was measured, and the result of this examination proved 

 that the quantities of air in the tubes would have the volumes 0-48, C26, 0-29, 0-51 and 0-48 cubic 

 centimetres at a temperature and pressure of o° and 760 mra (the volume of each tube supposed to be 

 1 litre). It was impossible to avoid the inconvenience of the tubes being delivered with so much 

 air contained in them, as one single tube, at a trial made before the expedition commenced, proved 

 to be evacuated of air. 



By the foregoing ciphers will be seen, that the apparent increase of the quantity of nitrogen 

 very well may be attributed to the fact of the tubes not having been properly pumped out, and if 

 now — after the expedition has arrived home — the amount of nitrogen in the analysis is corrected 

 in such a manner that it becomes equal to that found on board, the amount of oxygen must also be 

 corrected with '/ 4 of the correction applied to the amount of nitrogen, the atmosphere being supposed 

 to contain 1 part of oxygen for every 4 parts of nitrogen, and we shall therefore obtain the following 

 quantities for the consumption of oxygen during the storing. 



Station Nr. 71, which shows such a large consumption of oxygen, was one of those at which 

 the greatest quantity of Plankton was acquired, and it will be seen that where the quantity of 

 Plankton is limited to a trifle, there is a corresponding small consumption of oxygen 

 during the storing, so that the method of preserving the water in glass-balloons affords sufficient 

 exactness, when the question is about water from great depths 1 ). 



All the hydrographic results acquired by gas-analyses, have nearly all been obtained by the 

 exclusive application of the two aforesaid theorems, namely, that in the case of the quantity of nitrogen, 

 the temperature of the water, when last it left the surface, can be determined in a 

 water-sample from the depth by means of the quantity of nitrogen held in it; and in 

 so far as regards the analyses of oxygen, that the quantity of this element as the water 



•J To avoid the influence of the Plankton, Prof. Petlersson has, such as it will appear from : Upplysningaf iil de hydro- 

 grafiske kartor og apparater m. m., som udstallas under n:o 2399 i Fiskerihallen (Sommercn 1897), with success employed 

 the method of covering the tubes internally with a layer of sublimate, which has the effect of killing all organisms. 



