228 



" After ignition, to destroy organic matter according to 

 general practice, the soil was digested with moderately 

 diluted muriatic or hydrochloric acid for an hour or two, 

 then diluted, and the soluble portion filtered off the 

 insoluble. In general, the insoluble portion of a soil 

 treated in this way consists of silicious sand, or small 

 particles of quartz mixed with some particles of other 

 minerals in so small a proportion as to make an analysis 

 quite unnecessary. In the present instance, however, the 

 portion insoluble in the acid was evidently a mineral 

 substance composed of silica combined with bases, and it 

 was necessary to analyze it also. The following is the 

 result [to Mr. Waldie's analysis I add, for the sake of com- 

 parison, an " Analysis of the Regur, or Black Soil of the 

 Deckan," taken from Ansted's Elementary Geology, 

 p. 343"] : 



Constituents of the Slack Soil No. I I. from Rehsulpore. 



