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During the violent fermentation which is neces- 

 sary for reducing farm-yard manure to the state in 

 which it is called short muck, not only a large quantity 

 of fluid, but likewise a gaseous matter is lost; so much 

 so that the dung is reduced one half, or two-thirds in 

 weight; and the principal elastic matter disengaged, is 

 carbonic acid with some ammonia; and both these, if 

 retained by the moisture in the soil, as has been stated 

 before, are capable of becoming an useful nourish- 

 ment of plants. 



In October, 1808, I filled a large retort capable 

 of containing three pints of water, with some hot fer- 

 menting manure, consisting principally of the litter 

 and dung of cattle; I adapted a small receiver to the 

 retort, and connected the whole with a mercurial pneu- 

 matic apparatus, so as to collect the condensible and 

 elastic fluids which might rise from the dung. The 

 receiver soon became lined with dew, and drops be- 

 gan in a few hours to trickle down the sides of it. 

 Elastic fluid likewise was generated; in three days 35 

 cubical inches had been formed, which when analy- 

 sed, were found to contain 21 cubical inches of car- 

 bonic acid, the remainder was hydrocarbonate mixed 

 with some azote, probably no more than existed in 

 the common air in the receiver. The fluid matter 

 collected in the receiver at the same time amounted 

 to nearly half an ounce. It had a saline taste, and a 

 disagreeable smell, and contained some acetate and 

 carbonate of ammonia. 



Finding such products given off from ferment- 

 ing litter, I introduced the beak of another retort 



