532 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



experiments were made by the "method of mixtures," with 

 an apparatus consisting of an oven and a calorimeter, and in- 

 geniously arranged for the purpose. Coarse and fine sand, 

 powdered quartz, marble-dust, kaolin, and peat were tested. 

 He concludes that, of the constituents of the soil, compared 

 by weight, water affects its thermal capacity most, humus 

 (peat) next, while the kaolin (clay) and marble (carbonate of 

 lime) stand far below and near each other in their influence. 

 As regards fineness and coarseness of the soil, both theoretical 

 considerations and actual experiments led to the conclusion 

 that the size of the particles has no influence on the specific 

 heat (ForscJiungen auf clem Gebiete der Agrikulturphysik, i., 



109). 



Tlie Propagation of Heat in the Soil. 



Pott has conducted a long series of experiments on the 

 propagation of heat in the soil by conduction, working with 

 the chief constituents of soils quartz, clay (kaolin), humus, 

 and carbonate of lime. The quartz was the best, and carbon- 

 ate of lime the poorest, conductor. Dense, compact soils con- 

 duct heat better than looser, coarser better than finer, and 

 moist better than dry soils. Stones increase the conducting 

 power. It appears, however, that the conducting power of 

 soils for h.eat is not so great as has sometimes been supposed 

 {Landw. Vs.-St., xx., 273). 



Haberlandt has reported some new experiments upon the 

 relative conducting power of wet and dry soil. He concludes 

 that (1) the conducting power is greater in wet soil than in 

 dry ; (2) at high temperatures the greater conducting power 

 of the wet soil is more than counterbalanced by the greater 

 evaporation ; (3) the temperature at which these two factors 

 are in equilibrium i. e.,at which the soil loses as much heat 

 by evaporation as it gains by conduction is highest in sandy, 

 and lowest in peaty, soils; and (4) the differences in tempera- 

 ture between dry and wet soil are very small, not exceeding 

 1.50 C. "The characterizing of moist soils as 'cold' is 

 therefore out of the question." 



Effect of Compactness and Looseness of the Soil upon its Tempera- 

 ture. 



An elaborate and extremely interesting series of investiga- 

 tions on this subject has been made by Wollny. Boxes 1 



