64 



cannot compare one soil with another, or the part of a 

 soil analysed with the land from which it is taken. 



Lapidaries guess pretty well of hard Stones by sight with 

 practice, so should those concerned in agriculture. Indeed 

 it would be very convenient if we could compare a written 

 analysis, for instance, soil taken from Sheffield Place, 

 remarkable for producing flourishing Oaks, analysed by 

 Davy, and found to consist of 



Water 3 



Silex 54 



Alumine . ... 28 



Carbonate of Lime . 3 



Oxide of Iron ... 5 



Decomposing matter . 4 



Loss 3 



100 



and the Oak soil figured from Yorkshire : we might con- 

 ceive the five parts of Oxide of Iron to give the colour j 

 the Silex grittiness ; the Clay unctuosity ; the Lime taking 

 a part from its unctuosity as well as the Sand ; the Vegetable 

 a soft matter distinguished from both by a rotten and car- 

 bonaceous appearance. According to experience, his Oak 

 land would to me differ in being a little lighter-coloured, 

 having a little more chalky whiteness, or having a little 

 more Lime than ours contains, and perhaps being of a 

 finer grain. This may be learned best by experience ; ana- 

 lysis may prove it. 



