4O2 



SOILS. 



proportions of lime; while in the tropics, the intense leaching 

 process prevents lime from reaching any high absolute or 

 relative percentages, save where limestone formations prevail. 

 Moreover, the mode of preparation of the soil extracts for 

 analysis by Wohltmann, and by Miintz and Rousseaux, differ 

 so widely from that forming the basis of discussion of soil-com- 

 position in this volume, that it becomes necessary to make 

 separate allowances in each case ; since some of the ingredients, 

 phosphoric acid, lime and magnesia, are fully dissolved by 

 the weaker treatments, while others, e. g., potash are not, 

 and are therefore not directly comparable with the data ob- 

 tained in the writer's work. The analyses made in India by 

 Leather and others have apparently been made substantially 

 in accordance with the author's methods and may be considered 

 directly comparable. 



SOILS OF SAMOA AND KAMERUN. 



Wohltmann has investigated the soils of Samoa, notably 

 those of the main island of Upolu, under the auspices of the 

 German " Kolonial-Wirthschaftliche Komitee " in 1903, and 

 gives the results of his observations and analyses in a report 

 published at Berlin in 1904. The analyses are quite numerous, 

 but unfortunately are made by a special method which renders 

 them only partly comparable with those of any other analyst. 



Wohltmann's method is this : " 450 grams of fine earth (below 2 

 millimeters diameter) is treated for 48 hours with i-^- liters of cold 

 chlorhydric acid of 1.15 density. Another portion, designed for a fuller 

 determination of potash, is treated for one hour with the same acid, 

 boiling hot. Potash was determined in both soil extracts ; the hot 

 extract gave from one-third to twice the amount obtained in the cold 

 extraction." l 



Wohltmann justifies this method by the statement that it has yielded 

 him results more nearly in accord with experience than any other tried, 

 both with tropical and European soils. 



Under these conditions only a few of the determinations in Wohlt- 

 mann's analyses are directly comparable with those upon which the discus- 



1 Wohltmann states that the hot extraction sometimes yielded as muck as five 

 times more than the cold ; but no such case appears in his reports on Samoa and 

 Kamerun. 



