68 TALKS ON MANURES. 



" 12. Properly regulated, however, the fermentation of dung is 

 not attended with any great loss of nitrogen, nor of saline mineral 

 matters. 



" 13. During the fermentation of dung, nlmic, humic, and other 

 organic acids are formed, as well as gypsum, which fix the am- 

 monia generated in the decomposition of the nitrogenized con- 

 stituents of dung. 



" 14. During the fermentation of dung, the phosphate of lime 

 which it contains is rendered more soluble than in fresh manure. 



" 15. In the interior and heated portions of manure-heaps, am- 

 monia is given off; but, on passing into the external and cold lay- 

 ers of dung-heaps, the freo ammonia is retained in the heap. 



" 16. Ammonia is not given off from the surface of well-com- 

 pressed dung-heaps, but on tuming manure-heaps, it is wasted in 

 appreciable quantities. Dung-heaps, for this reason, should not 

 be turned more frequently than absolutely necessary. 



"17. No advantage appears to result from carrying on the fer- 

 mentation of dung too far, but every disadvantage. 



" 18. Farm-yard manure becomes deteriorated in value, when 

 kept in heaps exposed to the weather, the more the longer it is 

 kept. 



" 19. The Iocs in manuring matters, which is incurred in keep- 

 ing manure-heaps exposed to the weather, is not so much due to 

 the volatilization of ammonia as to the removal of ammoniacal 

 salts, soluble nitrogenizcd organic matters, and valuable mineral 

 matters, by the rain which falls in the period during which the 

 manure is kept. 



" 20. If ram. is excluded from dung-heaps, or little rain falls at 

 a time, the loss in ammonia is trifling, and no saline matters, of 

 course, are removed ; but, if much rain falls, especially if it de- 

 scends in heavy showers upon the dung-heap, a serious loss in 

 ammonia, soluble organic matter, phosphate of lime, and salts of 

 potash is incurred, and the manure becomes rapidly deteriorated 

 in value, whilst at the same time it is diminished in weight. 



" 21. Well-rotten dung is more readily affected by the deteriorat- 

 ing influence of rain than fresh manure. 



" 22. Practically speaking, all the essentially valuable manuring 

 constituents arc preserved by keeping farm-yard manure under 

 cover. 



" 23. If the animals have been supplied with plenty of litter, 

 fresh dung contains an insufficient quantity of water to induce an 

 active fermentation. In this case, fresh dung can not be properly 



