306 Alf Trolle. 



chlorine contents ol' which were determined onboard and found to 

 be almost equal to the amount in the normal water. 



The titrations in the winter of 1906/07 may thus also be con- 

 sidered to have been quite accurate, but after the summer of 1907 

 there seems to have been an error in the values found for the chlor- 

 ine contents, as there is a difference between the values determined 

 by titration onboard and those found at the Hydrographical Labor- 

 atory in Copenhagen after the return home, a difference which varies 

 between О^ОЗ^/оо and O'lS^/oo of the chlorine contents, the values 

 found in the Hydrographical Laboratory being always greater than 

 those which I had found onboard. 



The reason for this difference I imagine to be, that some evap- 

 oration of the normal water may gradually have taken place, mak- 

 ing it more saline in the later investigations. Each time the normal 

 water was used the stopper had to be taken off, naturally, and this 

 may have led to a very slight evaporation. 



The samples of the following series XXX— XXXIII, XXV— 

 XXXVII, XXXIX. XLVIl— L and LIIl were titrated onboard in 

 the course of the winter 1907/08 without control titrations being 

 made in Copenhagen. For all these series, therefore, the values of 

 chlorine "/qo are probably too low in the Tables. The exact values 

 may be considered to be on an average ca. 0'08 7oo higher. 



The areometers were used for surface determinations. 



4. Corrections. 



The followings corrections have been applied to the temperatures 

 recorded. 



1. The correction from the control certificates from the Physi- 

 kalisch-Technische Reichsanstalt in Charlottenburg. 



2. Correction for the coohng caused by expansion owing to 

 diminution of pressure in the sample taken. This correction has 

 been applied for depths of 500 m. and more and is in agreement with 

 the Table p. 6 in Nansen : Norwegian North Polar Expedition, Vol. IX. 



Depth 500 m. : correction + 0-02° 

 „ 1000 „ „ + 0-04^ 



1500 „ „ + 0-05° 



2000 „ „ + 0-06° 



2400 „ ,. + 0-07° 



3. Correction for cooling caused by expansion of the fixed parts of 

 the water-bottle. The Table is in agreement with the Table in Nan- 

 sen and Helland-Hansen : The Norwegian Sea, p. 48. 

 Depth 500 m. : correction -f 0'01° 

 „ 1000,, „ +0-02° 



1500 „ „ + 0-03° 



2000 „ „ + 0-03° 



., 2400 „ „ + 0-04° 



