FUNCTION.] 



SOLID MATTERS. 



275 



differences which we find in the germination of seeds and the 

 growth of plants in the shade and sunshine, are due in a great 

 measure to the influence of nitrogen. 



According to Pay en (Comptes rendus, viii. 60.), those 

 manures are the most efficient which are richest in nitrogen, 

 for he considers that plants are generally able to obtain, in 

 most cultivated soils, a sufficient supply of the other principles 

 necessary to their existence, without the addition of manure. 

 But this does not quite agree with an assertion of Boussin- 

 gault, that although some plants rob the air of a considerable 

 quantity of nitrogen, yet others do not assimilate it at all. 

 (76. 55.) 



The solid matters found in the ashes of plants vary greatly 

 from species to species, and are of different degrees of import- 

 ance in different cases. This will be evident from the follow- 

 ing table, which indicates the proportion of the more common 

 substances discovered by chemists in 100,000 parts of the 

 dried plant. The first ten analyses are given upon the 

 authority of Sprengel ; the next eight are taken from Pro- 

 fessor Edward Solly's Rural Chemistry : 



T 2 



