E. J. Rfssell and E. H. Richards 



517 



being added to keep the heap perpetually moist without, however, 

 putting on any excess to drain away. The result may have been to 

 diminish the evaporation of ammonia, but it certainly did not diminish 

 the loss of nitrogen: on the contrary the loss rose from 7-5 to 13-6 %, 

 all of which fell on the more complex compounds : 



Highest temperature 



Loss of dry matter, original dry matter being = 100 



Loss of nitrogen, original nitrogen being = 100 



Of which i—NH, lost 



amide gained 



other compounds lost 



Effect of exposure. The heaps already described were all kept under 

 cover. A similar set was put up close by, but exposed on all sides to 

 wind, rain, and sun. The first effect was to cause the outer layer to 



Z2L 



7 



S8 



Fig- 4. Changes in nitrogen compounds in farmyard manure (mixed) kept 



for six months, at Woking. 



34—2 



