Farmyard Manure. 67 



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 for 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 with 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, farmyard manure (about 14 days) -V T ,. 



old) examined Nov. 3rd, 1854 .. } No reactlon ' 

 Well-rotten dung taken from the bottom i 



of manure-pit on the 5th of Dec., 1854 j " 



Analyses made February 14th, 1855. 



No - L> fsh farmyard 



Experimental heap, No. Ill, well-rotten Nitric acid distinctly present ap- 

 P dung exposed *.. .. '. ..... E^.^.&*& 



Analyses made April 30th, 1855. 



Experimental heap. No. I., fresh manure! TV ,. 



exposed f Distinct tra ces of nitric acid. 



Experimental heap, No. II., fresh manure ) 



under shed ............ j ' ' 



Experimental heap, No. III., fresh manure i NQ reaction> 



Experimental heap. No. IV., well-rotten) TV ,. f .. . 



dung exposed .. .. .. .. .. } Distinct traces of nitrjc acid. 



Analyses made August 23rd, 1855. 



Experimental heap, No. I., fresh manure) .. ,. .. . 



PVT.OP/I f *H8tinct traces of nitric acid. 



C'Xposeu. .. .. .. .. .. .. j 



Experimental heap, No. II., fresh manure) m i . - r 



under shed.. . .. ...... } The same as in May. 



Experimental heap, No. III., fresh manure) A f . . 

 spread out ............ j A la lce ' 



Experimental heap, No. IV., well-rotten I Stronger reaction of nitric acid, 

 dung exposed .......... J than in May. 



It will be seen that there was no nitric acid present in the 

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

 the pit ; and, as traces of nitrates were detected in the manure 

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

 follow that access of air is essential for the formation of nitrates 



