3° 



HYDROGRAFI. 



common titration with chromate of potash as index, it can easily be understood that by this mode of 

 procedure a far greater exactness may be attained, such as shown by the experiment. Being of import- 

 ance that not only the relative amount of chlorine should be determined, but also that we get a state- 

 ment which may be compared with the determinations of other hydrographers, I ashed Professor Petters- 

 son in Stockholm for a sample of water of which the amount of chlorine was stated. Professor 

 Ptttcrsson was kind enough to send me a sample of this kind, the amount of chlorine of which was 

 determined by weight analysis. I have by means of the last mentioned mode of titration made a com- 

 parison between this sample and the one, in proportion to which the determinations of chlorine 

 were made an board, so that all the measurings refer to the water sample analysed by Professor 

 Pcttcrsson. 



ANALYSIS OF THE NITROGEN & OXYGEN CONTAINED IN SEA-WATER. 



The well known hydrographical mode of investigation, which has developed itself of late years, 

 and by which great results have been attained, specially by Professor Otto Pcttersson'' 's researches, 

 has principally served as a model for the hydrographical investigations made by the Ingolf Ex- 

 pedition. Owing to this, it was quite natural that preliminary arrangements were made for the 

 execntion of gas analyses. Doctor Rordam put me up to Professor Pctterson^s method, and 

 showed me the way in which the analyses could be executed in accordance with this, and he directed 

 likewise my attention to such other analyses, as it might be of interest to have made. In conse- 

 quence of this, the vessel carried with it on the voyages a great deal of hermetically sealed glass- 

 balloons, from which the air had been expelled by means of mercury, and which were delivered ready 

 made from the glass-works. In 1895 water samples were deposited in balloons of this kind, and the 

 gas analyses were undertaken when the ship had arrived home, and in April I received a report from 

 «the Commission for the Exploration of the Danish seas, which report was made out by 

 Doctor Rordam. On page 105 — 107, Doctor Rordam gives an account of some of the gas-analyses 

 executed by him, and he writes on this subject as follows: Seen from an analytical point of view, no 

 objection can be made against the correctness of the analyses, and there is every reason to believe 

 that they give as true a statement as practically possible, so that they really indicate the 

 quantities of gases that were present in the water-samples at the time they were 

 analysed. On the other hand, it is a question whether these quantities of gases are the same as 

 those contained in situ in the sea. The greatly varying percentage of oxygen seems to imply that 

 internal transitions have taken place in the samples between the oxygen of the sea-water and the 

 organical, partly organized elements of the water. As according to this, Doctor Rordam had directed 

 the attention to the fact of its being possible that internal transitions might take place in the samples 

 during the storing of same, I considered it necessary to make the analyses on board, and I had there- 

 fore an apparatus made, which is described in the following. All the analyses in 1896 were made by 

 this apparatus. 



The gas-analysis-apparatus is represented skeleton like on plate II. The principal 



