On Ar/riculfura] Clicmistri/. 



243 



Supevphospbate of lime, 350 lbs. ; phospbate of magnesia, 420 lbs. 

 Saper])bospbate of lime, 350 lbs.: ])hosphate of soda, 325 lbs. 

 Snperphospbate of lime, 350 lbs. ; pbospliate of potass, 375 lbs. 

 Superpbosphate of lime, 560 lbs.; silicate of potass, 220 lbs. 

 Saperpbospbate of lime. 350 lbs. ; phosphate of magnesia, "210 lbs. ;"1 



phosphate of soda, 162^ lbs " . j 



Superphosphate of lime, 350 lbs. ; phosphate of magnesia, 210 lbs. :1 



phosphate of potass, 1S7 lbs. J 



Saperpbospbate of lime, 350 lbs. ; phosphate of magnesia, 210 lbs. \ 



silicate of potass, 275 lbs J 



Super})hospbate of lime, 350 lbs. ; phosphate of magnesia, 168 lbs. ; 1 



phosphate of potass, 150 lbs. ; silicate of potass, 110 lbs. . j 



The greatest increase obtained by these mineral manures over 

 the natural produce of the soil was less than 2 bushels of wheat 

 and 84 lbs. of straw. The effect of minerals obtained from a 

 more natural manuring source (the combustion of dung), gave a 

 similar result. A quantity of farm-yard dung was weighed into 

 two portions, at the rate of 14 tons each per acre, one being 

 burnt to ashes, and the other ploughed into the soil. The results 

 were as under : — 





Bushels 



Pounds 





of Grain . 



of Straw. 







U76 



Ash of li tons of farm-yard dung . . . 



16 



1104 



The absence of any agricultural increase of produce through- 

 out this series of experiments might be said to arise either from 

 some defect in the mineral constitution of the manures, or from 

 the minerals in the soil not being in a proper state for the wheat 

 to assimilate them : but if, as is seen in the following table, the 

 addition of an ammoniacal salt can produce an increase of corn 

 and straw to a considerable extent, the minerals must have been 

 in a state available for the plant : — 



Bushels 

 of Grain. 



Pounds 

 of Straw. 



1 64 

 16| 



1100 

 1172 

 1180 

 1112 



163 



1116 



17i 



1204 



17 



1176 



1'^ 



1240 



1. Superphospliate of lime, 635 lbs. ; sulphate of ammonia, 65 lbs 

 .2. Superphosphate of lime, 350 lbs.: phosphate of magnesia, 84 



lbs. ; phosphate of soda, 75 lbs. ; silicate of potass, 110 lbs.; 



sulphate of ammonia, 65 lbs. ............... 



3, Superphosphate of lime, 350 lbs.;, phosphate of magnesia, SI 



lbs. ; phosphate of soda, 75 lbs. ; silicate of potass, 110 lbs. : 

 rape-cake. 153 lbs. 



4. Superphosphate of lime, 350 lbs. ; phosphate of magnesia, 106 "i 



lbs.; phosphate of soda, SO lbs. ; silicate of potass, 1 10 lbs. ; > 

 sulphate of ammonia, SO lbs. ........ ^ 



R 2 



