PHYSICS 



opened indirectly by the outer passage to the interior of 

 the hut. Moist air from the living-quarters, kept at a mean 

 temperature just above freezing-point, circulated through 

 the cracks around the door and entered the laboratory, 

 which for the most of the time maintained a mean tempera- 

 ture of 40° Fahr. to 50° Fahr. below freezing-point; 

 there the water vapour crystallised out, coating the walls 

 and passages with a thick formation of ice blades. The 

 result was exquisitely beautiful, but most undesirable, 

 finally making it necessary to abandon the room for every- 

 thing but ice work. 



In the same way ice formations appeared on the 

 colder portions of the interior of the hut. In crevasses 

 beautifully formed crystals up to four inches in length 

 were found developed on the walls from circulating 

 vapour. Along cracks in the sea ice during winter such 

 formations were abundantly produced. In such situations 

 the sea- water actually "smokes," an effect due to the 

 freezing out of abundant water vapour present in the 

 warmer air ascending from it. This condensation pro- 

 duces beautiful fern-like crystal formations, not only on 

 the sides of the cracks but also on the frozen sea surface 

 itself ; these ice flowers are best developed when the sur- 

 face waters freeze most rapidly. 



During the formation of the surface ice some of the 

 sea salts are squeezed upward through capillary cracks to 

 the surface and there in the form of concentrated brine 

 eventually freeze as cryo-hydrates and form nuclei for 

 additions from atmospheric-water vapour. The net 

 result is the production of little rosette-shaped aggre- 

 gates of radiating crystal blades, which were met with up 

 to two inches in height. 



As a rule, however, the moisture is precipitated from 

 the atmosphere in the form of snow. Rain is quite un- 



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