150 URINE. 



and the hydrogen either unites with carbon to 

 form the essential or fixed oil of the plant, or 

 is evaporated through the leaves as useless 

 matter. 



That such is the effect of ammonia or nitro- 

 gen, applied under any circumstance, in which 

 the salt is soluble, can be easily demonstrated, 

 by applying it to any crop, when it will 

 speedily assume a dark green colour and lux- 

 uriant appearance, which is the peculiar effect 

 of the nitrogen alone, and which is forcibly il- 

 lustrated in the dark green circles, popularly 

 called fairy rings, which exist on the downs, 

 and which owe their dark colour entirely to 

 the mushroom or fungus spawn, existing under 

 the surface, and which spawn consists almost 

 wholly of nitrogen, and communicates its pro- 

 perty to the grass growing above. 



The specific action of nitrogen also, by en- 

 dowing the plant with greater energy, enables 

 it to assimilate more carbon from the atmo- 

 sphere, and thus the addition of this manure, 

 which is in every respect an essential to plants, 

 gives it a greater power of assimilating another 

 substance of almost equal importance as itself. 



In concluding our notice of this manure we 

 can only repeat that the liquid and solid excre- 

 ment of man used together, and prepared in the 

 way we have described, forms, from its combi- 

 nation of ammonial salts with the phosphates 

 of magnesia and soda, the most valuable com- 

 pound that can be devised, and its extensive 

 use, will confer a double benefit to the farmer 

 and to the public, as well by the removal of 

 matter which is now only considered as a nui- 

 sance, as by increasing the produce of the soil. 



