352 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



THE ATMOSPHERE AS RELATED TO VEGETATION. 

 Nitrogen Compounds Brought to Soil by Snow. 



Messrs. Ballart and Comstock report some determinations 

 of the amounts of nitrogen compounds in snow, conduct- 

 ed under the direction of Professor Perkins, of Union Col- 

 lege. Three samples of fresh snow gave, on the average, in 

 100,000 parts by weight, 0.04G5 part of ammonia, and 0.041 

 part of organic nitrogen. From these figures the total amount 

 of ammonia and of organic nitrogen to the acre for each inch 

 of water (that is, melted snow) is found to be ammonia, 

 0.1055 pound; organic nitrogen, 0.093 pound. 



Using as a basis the observations at the Dudley Observa- 

 tory, according to which the total snowfall last winter (No- 

 vember 1, 1876, to March 31, 1877) was five feet eight inches, 

 and reckoning ten inches of snow equal to one inch of water, 

 the authors calculate that in this winter's snowfall " there 

 could not have been more than 0.69419 pound of ammonia 

 and 0.61194 pound of organic nitrogen to the acre. This 

 shows that though snow may be a great protective to the 

 ground, still it does not act as a very powerful or rich ma- 

 nure. 



Influence of Forests upon Rainfall and Temperature. 



Fautrat has continued his observations upon the tempera- 

 ture, the hygroscopic condition of the atmosphere, and the 

 rainfall over forests, as compared with those over adjoin- 

 ing open territory, noting at the same time the amounts of 

 water in the soils. He had previously found more moisture 

 and more rainfall over a forest of deciduous trees than over 

 open land. The amount of water received by the forest soil 

 was less, however, because the trees kept part of the rain 

 from reaching it. But, on the other hand, the tree-covering 

 so diminished the evaporation from the forest soil that the 

 latter retained much more water than did the open land. 

 Similar observations have since been made upon forests of 

 evergreen trees and adjoining open land. The results are 

 similar in kind to those with deciduous trees, but more mark- 

 ed. The rainfall over a pine forest was, on the average, 10 

 per cent., and that over a forest of oak and beech 5 per cent, 

 more than over adjoining open fields. The total rainfall 



