SOIL HEAT 



295 



Lang 1 (1 78) 

 Coarse sand 

 Limestone soil 

 Humous soil . 

 Garden soil 

 Peat .... 



Patten 2 (1909) 



.1980 Norfolk sand . . .1848 

 .2490 Podunk fine sandy 



.2570 loam 1828 



.2670 Hagerstown loam .1914 

 .4770 Leonardtown loam .1944 # 

 Galveston clay . .2097 



Bouyoucos 3 (1913) 



Sand 1929 



Gravel 2045 



Clay 2059 



Loam 2154 



Peat 2525 



212. Variations of specific heat. — These figures show 

 a considerable amount of variation, part of which is of 

 course due (1) to inaccuracies in the designation of the 

 materials used, (2) to differences in methods, and (3) 

 to differences in technique: Allowing for these probable 

 errors, there still seem to be other factors involved. One 

 of these might be texture, since, according to the earlier 

 investigators, the finer mineral soils seem to possess a 

 higher specific heat. The data of Bouyoucos and Patten, 

 however, seem to controvert this assumption. An in- 

 vestigation more to the point is that of Ulrich. 4 In work- 



1 Lang, C. Ueber Warme Capacitat der Bodenconstitu- 

 enten. Forsch. a. d. Gebiete d. Agri.-Physik, Band I, Seite 

 109-147. 1878. 



2 Patten, H. E. Heat Transference in Soils. U. S. D. A., 

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



3 Bouyoucos, G . J. An Investigation of Soil Temperature. 

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



4 Ulrich, R. Untersuchungen iiber die Warmekapazitat 

 der Bodenkonstituenten. Forsch. a. d. Geb. d. Agri.-Physik, 

 Band 17, Seite 1-31. 1894. 



