VEGA-EXPEDITIONENS V KT Ii N S K A FL IG A AHBETKN. 



253 



of the sea, the 3"' August 1881, a deepsounding was made by 

 the Holland expedition on board of the Willeni Barentz * with 

 the foUowino; result. 



The abrupt change in the qnality of the water, which 

 takes place at a depth of 2 fathoms, is very remarkable. 

 Another example. In the beginning of July 1879 the ice began 

 to thaw at Pitlekaj, the winter harbour of the Vega. The 

 7"" of that month, 11 days before the ship escaped from its icy 

 iDOundaries, the saltness of the waterstrata was found to be: 



These eonsiderations led me to adopt the following plan. 

 Wishing to direct the experimental research principally to 

 those phenomena, which are found to be of preponderating 

 importance in nature, I resolved to study separately the 

 change of heat and volume by the freezing of 



1. pure water (chapter 3, Tab: I, II, III.) 



2. brackish w^ater of little saltness (chapter 4, Tab: IV, V.) 



3. oceanwater of ordinary saltness (chapter 4, Tab: VI.). 

 I will first devote a couple of lines to tlie results already 



obtained by other investigators. 



The properties "of pure water being a subject of funda- 

 mental importance to ph^-^sical science as well as to h3^dro- 



* Verslagen omtrent den vierden tocht van de "Willem Barentz naer 

 de Yszee in den Zoomer van 1881., page 52. The author observes: »het 

 warme lichte water van de oppervlakte is sleclits een groote vaam diep en 

 beweegt zioh vrij zeker in eene andere riehting als de koude onderstroom». 



