Chemical and Physical Notes 31 



which describe the freezing of sea-water under severe cold, are 

 of special interest : 



Page 55. The author is here describing the ice which 



surrounded the " Tegetthoff " during the winter. Referring 



to the openings which occur in it from time to time and 

 without apparent reason, he says: 



" If the cold is very intense, then such quantities of vapour rise from 

 the water, so soon as it comes in contact with the air, that it looks as if 

 a veil had been spread over the surface of the water. The masses of 

 vapour which rise are so dense that it looks as if the opening of the ice 

 were filled with hot water. 



" This does not, however, last long. The evaporation of the water 

 which furnishes the vapour removes heat from the water and assists the 

 cold of the air in producing a covering of young ice. In a very short 

 time the surface of the water begins to get thick, and threads like 

 a spider's web run out from the edge of the old ice towards the middle. 

 The covering which at first was thin and pasty acquires consistence and 

 thickness ; the production of vapour diminishes, and soon ceases. 



" At this stage the salt-water ice is a pasty mass, which follows every 

 surface movement of the water on which it floats. With increasing thick- 

 ness this ice-mass acquires greater consistence and becomes tougher, 

 but even with very intense cold it does not become sufficiently strong to 

 bear the weight of a man with safety until after thirty to thirty-six hours. 

 With a temperature of - 40 C. the new ice, even after twelve hours, is 

 still so soft that, in spite of its thickness, a stick can be easily thrust 

 through it. On December 13, 1872, the ice had in sixty hours attained 

 a thickness of 20 centimetres, the temperature being 35 C. But even 

 with this thickness it is still in no way brittle, but is so pasty that it gives 

 way under the weight of a man, without breaking. It gives the impression 

 that one is walking on well-stretched leather, and it keeps this leathery 

 character for a long time. Even after fourteen days, when its thickness 

 is over half a metre, it does not break when exposed to moderate 

 pressure, but crumples up with undulating folds. An expanse of young 

 ice in this state looks as if the water, when in motion, had been surprised 

 by the cold and every wave had suddenly been turned into ice. 



"This persistent viscosity is caused by the large amount of salt which 

 remains in the upper layers of the ice frozen by intense cold, and of the 

 moisture which it attracts. In the formation of each ice-crystal, the salt 

 is completely excluded. When the ice formation takes place very rapidly, 

 under the influence of very low temperature, a large number of ice-crystals 

 are formed in a very short time, and much of the salter brine remains 

 entangled in them. Consequently the ice covering which first forms 

 consists of loose ice-crystals, mixed with the brine from which they have 



