382 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



to 24, under a turfed and under a bare soil, was always differ- 

 ent in the two ; and that, during all the months of the year, 

 the temperature of the sodded soil was generally higher than 

 that under the denuded surface. 



A farther inquiry was entered into as to the effect pro- 

 duced upon similar soils by a rainy season, the observations 

 beino; made for two months, Avhen the rain was almost con- 

 tinuous ; and it was found that, during November and De- 

 cember, 1872, the rain being almost constant, the mean tem- 

 perature of the soil covered with vegetation, up to the depth 

 of 24 inches, was nearly always superior to that of the de- 

 nuded soil at the same depth. In November, the tempera- 

 ture at 6 o'clock in the morning, at different depths, was 

 generally nearly 2 degrees Fahr. higher under the sod than 

 iinder the denuded soil, down to a depth of about 12 inches. 

 At 3 o'clock P.M. the difference was less. During a clear 

 sky the temperature under the sodded surface was nearly 1^ 

 degrees below the mean temperature, and 1.80 to 3.60 de- 

 grees above that of the bare surface. With a cloudy sky, the 

 temperature of the covered soil equaled that of the air ; dur- 

 ing rainy days the temperature under the sodded surface, at 

 a depth of 20 inches, was 1.15 degrees less than that of the 

 air; under the sodded soil the temperature w^as about the 

 same. 



As a general rule, it was found that the covered soil 

 was about 1.80 degrees Fahr. warmer than the uncovered, 

 whatever the nature of its composition, during a moist and 

 rainy season. This may, perhaps, be explained on the suppo- 

 sition that, when soil is covered with vegetation, the roots of 

 the latter form a kind of felting which prevents the ready 

 passage of the rain having the temperature of the air, so that 

 the covered soil assumes the temperature of the air more 

 slowly than the uncovered. 6 B^ February 10, 1873, 31 j. 



PEODUCTIOX OF NITRITES IN THE SOIL. 



-In an article by Dr. Jeannel upon the production of ni- 

 trites in the soil, and upon the functions of humus, it is stated 

 that the calcareous humus, or the vegetable earth, in drying, 

 determines the combination of the elements of the atmos- 

 phere, in the form of nitric acid, w^hich is immediately satu- 

 rated by the lime. In this way may be explained the barren- 



