36 HYDROGRAPHY. 



when the ship is rolling, as when it is in a smooth sea. The only inconvenience occasioned by the 

 rolling of the vessel, is, to pour sulphuric acid into T z and potash into T 2 and T 3 . 



As soon as the water bottle, after its being hauled up, had been taken into the laboratory, 

 it was properly secured between some wooden stanchions in the table, and the water was, in such 

 a manner as has been described, sucked into the apparatus and made subject to boiling and analysis, 

 so that the water could not be warmed to any perceptible degree, or give up any of the gas contained 

 in it, before the examination of the sample took place. A few times the analysis could not be made 

 before half an hour after the sample had been hauled up. The water then remained in the water- 

 bottle, which was placed on the deck to prevent it from being warmed. 



The determinations of temperature and salinity as well as the analysis of gases mentioned in 

 the foregoing, have all been made on board, and of the gentlemen who assisted me in this work, I 

 have the pleasure of directing the attention to the following. On the first voyage in 1895, Mr. Stgurd 

 Wandel, painter, took part in the expedition as draughtsman and assisted me in many ways, speci- 

 ally with my work at the stations. On the next voyage in 1896, my work was increased with the 

 execution of the analyses of the gases, and the titrations were therefore principally executed by Mr. 

 A. Blad, assistant surgeon on board the Ingolf. From the following will be seen that no exertion 

 has been spared to execute this comprehensive work with the greatest punctuality and accuracy. 



When I commenced my researches concerning the relations between the plankton of the sur- 

 face waters and the amount of oxygen held in these waters, Mr. Liebmann, undergraduate, and the 

 draughtsman of the expedition on the second voyage, was entrusted with the collection of Plankton 

 and the temporary examination of same, but shortly after the voyage had commenced, he was relieved 

 by the botanist of the expedition Mr. Ostenfeld-Hansen, M. A, together with whom I made some of 

 the investigations described in the following. 



The greater part of the chemical analyses mentioned in this work, and which have been 

 executed after the expedition had come home, were made by Mr. Julius Petersen, cand. polyt. and 

 assistant at the chemical laboratory of the Polytecnical Academy. Mr. Jorg. Jorgcnscn, teacher, and 

 Mr. Absalon Larsen, M. A., have assisted me with the construction of the charts and tables. 



Finally I render my best thanks to the gentlemen who assisted me in the execution of the 

 work which I could not manage myself, what by want of time and knowledge of all the branches 

 of the cases concerned. 



