418 EXPERIMENT STATION RECORD. 



(5) In samples poor in clay the clay should be weighed directly, hut iu 

 samples rich iu clay it may be estimated by differences. 



(6) The humus content should be computed as one-half of the carbon dioxid 

 obtained in ordinary organic analysis for carbon determination. 



(7) Compare the trituration of the sample with the thumb according to 

 Atterberg with that by shaking according to Hissinli. 



The new classification of the granulation products in mechanical analysis. 

 J. KoPECKY {Internat. Mitt. Bodenk., 4 (1914), No. 2-3, pp. 199-202) .—The 

 author criticizes the classification of soil grains noted above, compares it with 

 the old classification according to Schone, and concludes that the modification 

 of the washing process and the rinsing apparatus is not necessary or justified. 



Vegetation and agricultural soil, G. de Angeles d'Ossat (Atti R. Accad. 

 Lincei, Rend. CI. Sci. Fis., Mat. e Nat., 5 ser., 22 {1913), I, No. 1, pp. 876-878, 

 fig, J). — The author concludes from his observations of natural soils that the 

 vegetation best adapted to a soil can not be accurately determined from a 

 geological map of the soil area, owing to the many physical, mechanical, and 

 more particularly, chemical changes to which the original rock may be sub- 

 jected during the transformation into agricultural soil. 



The radio-activity of some type soils of the United States, R. B. Moore 

 (Jour. Indus, and Engin. Chem., 6 {1914), No. 5, pp. 370-374, fig- i).— The 

 author reports chemical examinations of samples of several type soils of the 

 United States to determine their radium and thorium contents. 



Of the 7 types examined for radium, the soil of 4 was more active than the 

 subsoil, while in the other 3 the reverse was true. The average activity of the 

 soils was 1.97X10'", and of the subsoils 1.52X10"". 



" There seems to be a fairly definite relationship between the activity and the 

 combined amounts of barium and sti*ontium. In the majority of cases the soil 

 or subsoil which has the highest activity also has the largest amount of barium 

 plus strontium. . . . The same reaction holds fairly well with the amount of 

 sulphur present. . . . Since radium has an insoluble sulphate, which precipi- 

 tates with the sulphates of barium and strontium, the results seem to indicate 

 that radium in the soil is very largely, if not entirely, in the form of sulphate." 



The thorium determinations in five of the types showed small variations and 

 " seem to indicate that soils contain more thorium than most rocks." 



Olifants River irrigation scheme (Van Rhynsdorp division). Flying agri- 

 cultural survey of the soils of the irrigable area, C. F. Juritz {Union So. 

 Africa Dept. Agr. Sci. Bui. 5 {1914), pp. 30; Agr. Jour. Union So. Africa, 7 

 {1914), ^0. 4, pp. 541-546). — The prevailing soil types of the Van Rhynsdorp 

 division of the project are described and discussed with reference to mechanical 

 and physical structure and plant food and alkali content. The prevailing types 

 are the so-called Karroo soils, consisting of red sands and sandy loams, and 

 alluvial soils, consisting of drab-colored loams and fine sandy loams. The allu- 

 vial soils are generally of finer texture than the Karroo soils. " The average 

 alluvium contains only 31 per cent of material coarser than 1/10 of a milli- 

 meter, as against 68 per cent contained by the average ' Karroo ' soil. On the 

 other hand, no less than 54 per cent of the average alluvium is silt and clay 

 of finer grade than 1/20 of a milimeter, and in the ' Karroo' soils this averages 

 only 19 per cent." 



Of the two Karroo soils the sands are classed as much the poorer chemically 

 than the finer-grained sandy loams. Except in phosphorus content the Karroo 

 soils did not appear to differ greatly from the average alluvium in mineral 

 plant food content. The alluvial soils examined were not invariably rich in 

 plant food, and the most marked chemical deficiency found in all the soils 



