ORGANIC MANURE. 289 



deficient. It would be easy to divide all manures 

 into these three classes ; but it is more convenient to 

 divide them simply into the organic and the inor- 

 ganic; because many manures act in all these three 

 vrays at once, improving the texture of the soil and 

 supplying carbonic acid, ammonia, and saline matters. 



763. The Chinese, who are very economical of 

 their manure, apply it in small quantities at several 

 distinct periods to their plants, when they judge it to 

 be wanted ; it may in fact be said that they manure 

 their plants, whilst in Europe it is the custom to 

 manure the soil ; this must of necessity be the case, 

 where labor costs less than manure. 



764. Organic manures may in general terms be 

 described as consisting of any kind of organic matter 

 in a state of decay or putrefaction. Setting out with 

 the knowledge that organic matter consists of carbon, 

 oxygen, hydrogen, and nitrogen, it is not diflScult to 

 understand the changes produced by its decomposi- 

 tion. 



765. The complicated changes which organic 

 matters undergo in decomposing are generally divided 

 into four separate classes, namely: Fermentation, or 

 the formation of new compound substances by the 

 partial decomposition of a compound, the change 

 being induced or commenced in consequence of the 

 presence of some other decomposing matter ; Putre- 

 faction, or the complete decomposition of organic 

 matter and its conversion into different inorganic 

 compounds, such as water, ammonia, carbonic acidy 



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