22 



THE ORIGIN OF SOILS 



[chap. 



acid charged water, especially those containing much 

 lime, while those with much magnesia are the most 

 resistant ; the products of the action are kaolinite, 

 oxides of iron, and carbonates of lime and magnesia. 

 The following analysis (Ebelmar) show the chemical 

 change in the weathered layers of a basalt from 

 Bohemia and a greenstone or dolerite from Cornwall : 



The loss amounts to about 44 per cent, in the case 

 of the basalt, and 34 per cent, in that of the greenstone. 



Another example may be given of the analysis 

 (Hanamann) of a basalt from Bohemia, with that of 

 the weathered crust and of the resulting soil : 



