MANURES. 83 



shape of oxalate or phosphate of lime — bone 

 manure now so much used is phosj)hate of 

 lime. The salts of potash and soda are like- 

 wise found in abundance in plants, hence, 

 besides the power possessed by these and some 

 other salts of dissolving various substances 

 found in the earth so as to make them fit juices 

 for absorption by roots, they themselves are 

 valuable manures in the shape of common salt 

 muriate of soda) saltpetre, (nitrate of potash) 

 &c., but they should be applied in small 

 quantities. Ulmin or geine, a peculiar sub- 

 stance resulting chiefly from vegetable decom- 

 position and existing in abundance in peat and 

 in common manure, has lately been brought 

 into notoriety in the Geological reports of 

 different States, and represented as the essential 

 part of manure, without a supply of which to 

 vegetables all fruit will fail. 



Much direct experiment is still wanting to 

 ascertain the true value and operations of this 

 substance. The small knowledge hitherto pos- 

 sessed on the subject is however rather in favor 

 of the theory. 



Those who consider the chemical constituents 

 of a soil as the sole tests of its value for the growth 

 of plants, will be much in error in practice. 

 Minerals and metals or rather their oxides 



