232 



NATURE AND PROPERTIES OF SOILS 



rate of cooling in autumn, drainage influences, and like phe- 

 nomena. 



Specific heat data from different investigators do not show 

 the agreement that might be expected. 1 This is probably due 

 (1) to inaccuracies in the naming of the soils used, (2) to 

 difference in methods, and (3) to difficulties in technique. 

 Everything considered, the following table from Ulrich 2 dis- 

 plays in a suitable way the important specific heat phases: 



It is evident that specific heat is partially governed by the 

 organic matter of the soil and partially by texture and struc- 



specific heat is the number of calories necessary to raise the temperature 

 of one cubic centimeter of the substance one degree. In the case of 

 soil, weight specific heat may be changed to volume specific heat by 

 multiplying it by the volume weight, since volume weight is the weight 

 in grams of one cubic centimeter of dry soil. 



■* The following weight specific heats from Lang,* Patten t and Bou- 

 youcos t are interesting : 



Lang 

 Coarse sand 198 



Patten 



Sand 



,185 



Limestone soil. . . .249 Sandy loam .183 



Organic soil 257 



Garden soil 276 



Peat 477 



Loam 191 



Loam 194 



Clay 210 



Bouyoucos 



Sand 193 



Gravel 204 



Clay 206 



Loam 215 



Peat 252 



* Lang, C, trber Warme Capacitat der Bodeneonstituenten; Forsch. a. 

 d. Gebiete d. Agr.-Phys., Band I, Seite 109-147, 1878. 



t Patten, H. E., Beat Transference in Soils; U. S. Dept. Agr., Bur. 

 Soils, Bui. 59, p. 34, 1909. 



t Bouyoucos, G. J., An Investigation of Soil Temperature ; Mich. Agr. 

 Exp. Sta., Tech. Bui. 17, p. 12, 1913. 



3 Ulrich, K., TJntersuchungen uber Warmekapazitat der Bodenkonsti- 

 tuenten; Forsch. a. d. Gebiete d. Agr.-Phys., Band 17, Seite 1-31, 1894. 



