PETTERSSON, ON WATER AND ICE. 



level of the sea, contrary to the action of gravitation. This 

 umount of work, which must be executed at the cost of the 

 latent heat developed by the water [because it is the immediate 

 consequence of its freezing], is stored iip in the ice and can 

 not be expended before the moment of melting, when it is 

 transformed into actual energy or vis viva of the water par- 

 ticles, derived from the higher level of the ice-water relatively 

 to that of the surrounding sea, which, as ^kman justly 

 observedj must occasion a surface current. ' The ice, which the 



By the freezing of the water the surface of the ice-fioe is lifted the distance ac contrary 

 to the action of the gravitation [and of course also to the atmospheric pressure]. 66 is the 

 niveau of the ice-water after melting. The difference be causes the surface-current. At the 

 melting of ice in fresh water be is = 0. 



arctic current forces into the angle between the American 

 continent and the powerful stream from the Mexican Gulf, 

 must, when melted, spread över the ocean in north-easterly 

 direction. The rotation of the earth exercises upon this cur- 

 rent a directing, but nowhere an impelling force. - We are 

 accustomed to ascribe the movements of the currents of the 

 atmosphere and the ocean to the solar heat. True; but solar 

 heat can not be transformed into mechanic energy without the 

 conditions of the second principle of thermodynamics being 

 fulfilled. The cycle of heat performed by the freezing and 

 melting of ice is of a different nature from the cycle of free 

 heat in the water caused by radiation and refrigeration. 



' At the freezing of fresh M'ater, as for example rivers, lakes etc. . . 

 one part of the latent heat is hkewise transformed into work, which is 

 again changed into heat at the melting of the ice, ivithout giving rise to 

 any mechanic effects, or motion of the water, currents etc. 



^ See Guld ber g: Theorien for vandets og luftens strömninger paa 

 jordens overflade, Polytekn. Tidsskr. 1872. 



