316 PETTERSSON, ON WATER AND ICE. 



these substances will melt, one by one, and absorb heat in 

 so doing. Thus the thermal processes in the mäss of the ice- 

 floes will to a certain degree counteract the influence of the 

 sudden variations in temperature of the atmosphere. 



I have already mentioned the fact, that I found during 

 my dilatometric researches, that pure ice did assume the tem- 

 perature of the mercury-bath surprisingly soon, and that the 

 case was quite reversed, when I operated with ice containing 

 any amount of salt, especially at those temperatures, where it 

 upon cooling showed an abnormal expansion of volume. I 

 can not decide, whether sea-ice is really a worse conductor of 

 heat than pure ice, or if this behavior is due to the thermal 

 processes just alluded to, having no quantitative measure- 

 ments to j-udge from, hut I consider, that the sea-ice will be- 

 have in nature just as it did, when tested in m}' apparatus, 

 viz. very slowly propagate thermic impulses from without. 



There is every reason to believe, that the formation of 

 ice in that part of the arctic ocean north of Europé even 

 in winter-time is limited to very higli latitudes. In winter as 

 well as in summer a mighty stream of warm water sets in 

 between Scotland and Iceland sweeping the coast of Norway 

 (which is entirely free of ice) and spreading its waters unto 

 the coasts of Spitzbergen and Novaya Zemlya. Thereby the 

 freezing of the arctic ocean is prevented and delayed, until 

 very high latitudes. We know, that the old polar-ice is trans- 

 ported along the eastern shore of Greenland and America 

 to relatively low latitudes, where it melts by the combined 

 influence of a warmer atmosphere and a warmer sea. Thus the 

 melting of the sea-ice and the freezing of the sea-water are 

 processes of reverse order, which take place at widely distant 

 latitudes. The solar heat stored up in the ice by its lique- 

 faction at low latitudes is developed again at 70^ or 80° Lat. N. 

 by the latent heat of the freezing sea-water. Its effects will 

 naturally not consist in any raising of the temperature of the 

 sea, but indirectly it will counteract the heaping of great ice 

 masses north of Europé, because: 



»Water can not freeze to ice, even at its freezing point, if 

 it can not transfer its latent heat to a colder medium?» [Ed- 

 lund]. 



The influence of the Gulf-stream on the climate of Europé 

 is said to be a theme nearly worn out, but I think the influence 



