AIR WATER SOILS 423 



per cent. Of the laterite soils, 4 contained less than 0.01 per cent, 4 others 0.08 per 

 center less, and 4 others fair amounts. The Madras alluvial soils contained, as a 

 whole, somewhat more, there heing 0.08 per cent or more in 6 out of 10 samples, but 

 the other 4 contained only very small amounts. The coffee soils have doubtless been 

 well manured, and contained with one exception 0.1 per cent or more. The Assam 

 soils appear to be far better off in respect of phosphoric acid than any other soils in 

 India. In none of those examined could there be said to be a serious deficiency." 



By digestion of some of the soils in 1 per cent citric acid, according 

 to Dyer, it was found that "although the Indian soils have frequently 

 or generally a low proportion of total phosphoric acid, it is likely that 

 the proportion of available phosphoric acid is not usually deficient." 



With the exception of Assam soils, there is usually little organic 

 matter and nitrogen in Indian soils, under normal conditions. 



"Among the soils representing the Gfangetic alluvium, 3 out of 10 contain 0.05 per 

 centor a little more [of nitrogen], the rest less; among the alluvial soils from Madras, 

 2 contained about 0.1 per cent, and 2 contained about 0.05 per cent, but in the other 

 6 samples the proportion was much less. Of the 18 samples of regur soils, only 1 

 contained 0.05 per cent, the other 17 containing less; among the red soils from 

 Madras 1 contained 0.05, the other 5 less; among the 12 laterite soils not one con- 

 tained as much as 0.05 per cent, and most of them only about 0.03 per cent or less. 

 On the other hand the Assam soils contained uniformly high proportions of nitrogen, 

 and those soils which have had an opportunity of accumulating nitrogen contained 

 very fair amounts. The soils from Partabgarh contained 0.18, the surface soil at 

 Changa Manga 0.237, and the coffee soils from the Sheveroys 0.04 to 0.17.'' 



The judging of the physical properties of soils by means of 

 the heat -which they evolve when moistened, A. aIitscherlioh 



(Jour. Landu-., 4.6 (1898), Xo. .5', pp. 255-268). — This is essentially a sum- 

 mary of an inaugural dissertation presented at Kiel in 1898. When 

 dry soils are moistened a certain amount of heat is evolved (Benetzung- 

 swarme). Wilhelmy ' has shown that the amount of heat thus evolved 

 depends upon the size, form, and adhesion coefficient of the individual 

 soil particles. 



The author undertook to determine whether this property of soils 

 could be used for comparing their physical properties. For this pur- 

 pose 10 typical soils, classified on the basis of their actual agricultural 

 value as determined in practice, were subjected to mechanical and 

 chemical analysis and also tested with regard to the heat evolved on 

 moistening. The samples used for analysis were put through a sieve 

 having round holes 1.5 mm. in diameter, and air dried to constant weight. 

 The moisture was determined in 5 gin. of the air-dry material by dry- 

 ing in a vacuum over strong sulphuric acid. The Schloessing method 

 of analysis was followed in the main. Humus, however, was calculated 

 by Wolff's factor, 1.724, from the carbon as determined by Loges' 

 method. 2 In case of soils rich in humus the portion separated as clay 

 in mechanical analysis contained considerable amounts of humus. A 



'Ann.Phys. n. Chem. [Poggendorff], 119 (1828), p. 177; 122 (1829), p. 1. 

 *Landw. Vers. Stat., 28 (1883), p. 229. 



