AGRICULTURAL TEXT-BOOK. 



varying proportion of magnesia. Of these, only common 

 hme, plaster and marl, are of present interest to us in this part 

 of the country. 



Lime rocks are rarely pure, and they vary much in their ex 

 act composition. It is believed that those of Michigan have not 

 yet been analyzed. The following are specimens from Seneca 

 county, N. Y., examined by Mr. Delafield. 



Insoluble sand and clay, . . *& f ^4.0 &quot;Vo 



Alumina and peroxide of iron, . 1.4 230 260 90 



Carbonate of lime, . 90 . 53.5 600 no 



JfT*/ I* 2.8 5.5 2.0 



Oxide of manganese, . nonef none&amp;lt; 1Q 



Soluble saline matter, 14 12 24 



Phosphoric acid, . tracCf trace&amp;gt; Ql 



(Trans, of tf. y . Agricul. Socy., vol. x, p. 61 1 .) 



The following are analyses of English lime rocks made by 

 Prof. Johnston, in their imburned and burned states : 



BURNED H0.1. K0.2. 



Carbonate of lime, . 94 gG 



Sulphate of lime. . 23 032 



Carbonate of magnesia, - . : 26 () ^ 



Alumina and oxide of iron, . . 073 j 20 



Phosphate of lime, . ? ? 



Silica - 2.92 2.05 



BURNED - NO. 1. NO. 2 . 



^&amp;gt; . 89.93 88.85 



Magnesia, . l ^ (W3 



Sulphuric acid, - . 22 03Q 



Phosphoric acid, . .90 



Alumina and oxide of iron, - . j 533 j go 



Silicate in the state of silicate, - - 4 92 3 39 



Carbonic acid and moisture, - - 2.68 5 05 

 (Johnston on the use of lime in Agriculture ,p. 243.) 



^ We shall shortly mention the effect of burned and slaked 

 Hme upon the land. 



1. Mechanical ; it opens and renders free, stiff clays, and con- 



