Farmyard 3Ianure. 255 



In conclusion, I may mention that I have tested the various 

 experimental manures at different times for nitrates, and have 

 been able to detect the presence of nitric acid in most cases in 

 which the manure had been kept ior some time in contact with 

 the atmosphere. Under all circumstances, however, the propor- 

 tion of nitric acid appeared to amount to mere traces ; and, as I 

 am not acquainted Avith any accurate method of determining 

 minute quantities of nitric acid in so complex a mixture of sub- 

 stances as that of farmyard manure, I have not attempted to deter- 

 mine the amount of nitric acid in the manure quantitively. I 

 may be permitted, however, briefly to state the results of my 

 qualitative examinations : — 



Qualitative examination for Nitrates. 



Fresh faraiyard manure (about 14 daysi j^-^ reaction 



old) examined Xov. 3rd, 1854 .. j " 

 "Well-rotten dung taken from the Ijottom i 



of manure-pit on the 5th of Dec, 1854 ] ' " 



Analyses made Fehrnary 14th, 1855. 



Experimental heap, No. I., fresh farmyardj ^^^^^^^ ^^^^^^ ^^ ^^.^^.^ 



manure exposed J 



Experimental heap, Xo. II., fresh farm-| Douhtful trace of nitric acid. 



yard manure under sued j 



Experimental heap, Xo. III., well-rottenf ^^itric acid distinctly present, ap- 

 '■■, J ^' ' { parently ni larEjer proi:)ortiou 



dung exposed | thaninXo.I. ° ^ 



Analyses made April 30th, 1855. 



Experimental heap, Xo. I., fresh manure| Distinct traces of nitric acid. 



exposed J 



Experimental heap. No. II., fresh manure i 



under shed j ' ' ' ' 



Experimental heap, Xo. III., fresh mainu'C) -y- _g^^f-„.-, 



spread out j ^ 



Experimental heap, Xo. IV., well-rotten j Distinct traces of nitric acid. 



dung exposed J 



Analyses made August 23rd, 1855. 



Experimental heap, Xo. I., fresh manure) Distinct ti-aces of niti-ic acid. 



exposed ) 



Experimental heap, Xo. II., fresh manure) ,^,j^^ ^^^^ ^^ .^ 



under shed J •' 



Experimental heap, Xo. III., fresh manure) ^ j-^j^^ ^^^^^ 



spread out ) ' 



Expcriiiunt.al heap, Xo. lY., well-rotten) Stronger reaction of nitric acid, 



dung exposed J than in May. 



It will be seen tliat there was no nitric acid p)csont in the 

 fresh manure, nor in the rotten dung taken from the bottom of 

 the pit ; and, as traces of nitrates were detecte<l in the manure 

 after a three-months' exposure to the weather, it would seem to 

 follow that access of air is essential lor tb.e formation of nitrates 



