THE EVAPORATION OF SNOW AND ICE. 



The object of the series of experiments on the evaporation of 

 clear ice and snow is to determine to what degree the evapora- 

 tion is affected by (a) temperature, (b) amount of atmospheric 

 pressure, (c) velocity of wind, and (d) area of exposed surface. 



It has been assumed that the laws for the evaporation of solids 

 like ice follow those for liquids. Dalton states that: "Evapo- 

 ration is that process by which liquids and solids assume the 

 gaseous state at their free surfaces. The rate of evaporation 

 depends upon temperature of the liquid or solid, the extent of 

 the exposed surface, and the facility with which the gaseous 

 particles can escape from the neighborhood of the surface either 

 by diffusion through the air or by the motion of the air itself." 

 This is equivalent to saying that evaporation of liquids and solids 

 depends upon temperature, amount of exposed surface, atmos- 

 pheric pressure, humidity, and wind. 



The evaporation of a liquid may be seen at any time and that 

 of a solid such as ice is often seen in the winter and spring 

 when snow disappears with the temperature continually below 

 o C. Also some chemical substances such as camphor and 

 iodine evaporate without first passing into the liquid state. 



Two different methods were used in this experiment, which 

 continued throughout the first three weeks of the month of 

 March, 1906, whenever the temperature remained below o C. 

 During the first two weeks of the month the conditions were 

 quite favorable. Attempts were made previous to March ; but 

 the weather was so mild for a greater part of the winter months 

 Dec., Jan., and Feb. that nothing was accomplished from 

 which anv conclusions could be drawn. 



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