36 GEOLOGY OF SOIL. 



The whole number of soils comprised in the above table 

 is 413. 



Insoluble. 



Deducting the 146 soils of Massachusetts, \ -, „„„ 



the remaining 267 give an average of J ; 



By adding the soluble and insoluble, the \ 



result is, / 87 33' 



while 146 Massachusetts soils contain 89.30° 



The sum of the whole 413, . . . 176.642 

 And the average is , . . . 88.; 



This examination proves that the 146 soils of Massachusetts 

 represent very fairly the average mineral composition of the 

 Koil of the globe. 



The results of chemical analysis stated per cent, to two or 

 three places of decimals, give the farmer no idea of the 

 quantity of any element in an acre, at the usual depth of 

 cultivation. A simple rule will make this amount evident. 

 The weight of a cubic foot of dried soil is as follows : 

 Silicious sand, , . . . 111.3 pounds. 

 Calcareous sand, .... 113.6 " 



Sandy clay, 97.8 " 



Loamy clay, ..... 88.5 " 



Stiff clay, 80.3 « 



Slaty marl, 112. " 



Fertile mould, .... 68.7 « 



Common arable soil, .... 84.5 " 

 The average is 94.58, whicli in the ordinary wet state be- 

 comes 126.6. Multiply 43560 by the weight of a cubic foot 

 of soil, and divide the product by 12, the quotient is the 

 number of pounds per acre at one inch deep. 



Eead the results of analyses stated in 100 parts, deci- 

 mally, as whole numbers, and consider each ingredient as so 

 many pounds in every 100,000 lbs. of soil. 



Multiply any ingredient by the number of pounds in one 



