116 ON MANURES. 



the cause of the luxuriant effects which follow 

 their use. Jt is here needless to repeat the 

 effects produced by carbon and nitrogen on 

 vegetation ; the chapter devoted to each, will, 

 it is hoped, fully explain their uses in con- 

 nexion with the growth of plants. 



Peat ashes, owe all their fertilizing property 

 to the presence of 12 per cent, of gypsum, and 

 the remarks made when speaking of that sub- 

 stance, (p. 103) will fully apply here. Rain 

 is absolutely necessary, in all cases where 

 gypsum is applied, to produce the desired 

 effects ; it acts by dissolving the ammonia ab- 

 sorbed by the gypsum, and which is thus con- 

 veyed into the soil, there to be absorbed and 

 assimilated in the manner previously described. 



The analysis of peat ashes yields 12 per 

 cent, of sulphate of lime,— a sufficient quantity 

 to account for the beneficial results which fol- 

 low their use. 



The other products of the analysis consist of 

 40 parts of carbonate of lime. 



6 parts of salts of soda. 

 32 parts of si licious earth. 



3 parts of oxide of iron. 



7 loss. 



Blubber, fish, oils, fat, S^c. — The analysis of 

 these substances yields upwards of 70 per cent, 

 of carbon, on which all their fertilizing pro- 

 perty depends. The first requisite, therefore, 

 is so to mix them, that the carbon may become 

 available when applied to the soil, and not, as 

 in too many cases, so combined as to form 

 either an insoluble compound, or one which is 

 so readily found in nature as to render it quite 



