232 



OIL-CAKE. 



more accurately, the azotized substances (albumen, 

 etc.), of which it contains nearly as much as bone- 

 dust, and about one third as much as good guano. 

 To develop the forcing action contingent hereupon, 

 a previous putrefaction and conversion of the azo- 

 tized into ammoniacal combinations is here again 

 necessary ; but this ensues more rapidly in oil-cake 

 than in bones, because it is more easily penetrat- 

 ed by water and air, and hence it is not essential 

 to induce putrefactive decomposition before plough- 

 ing it into the ground. Experience agrees entirely 

 with the representation, that it acts more speedily 

 than bone-dust, but, on the other hand, more slowly 

 than guano ; as also with the statement, that its 

 principal effect takes place during the first year, ex- 

 cept, perhaps, in a very dry season, in which it does 

 not find in the earth the amount of moisture required 

 for its decomposition. 



After nitrogen, the action of oil-cake (in forming 

 the seed) is due to its contents of phosphoric acid. 

 Of this substance, however, it contains about five 

 times less than good guano, ten times less than 

 bone-dust, and twelve to fourteen times less than 

 bad bird -manure. That, moreover, the other inte- 

 grants met with — potash, soda, lime, as also the or- 

 ganic, humus-forming substances, and, in addition 

 to these, the common salt and gypsum that may 

 perhaps be present — increase the efficacious opera- 

 tion of oil-cake, cannot be denied ; nevertheless, the 

 same importance cannot be attributed to these in- 



