Farmyard Manure. 113 



circumstance that ammonia is given off only in the interior of the 

 heap and not from its surface, and also how it is that manure 

 which does not contain a trace of free ammonia at the heat of 

 boiling water gives off this gas in appreciable quantity. In the 

 course of this investigation, I was led to the chemical examina- 

 tion of the drainings of dung-heaps, and obtained results which, 

 I believe, are of sufficient interest to be recorded in a Journal 

 devoted to the promotion of good agricultural practice and sound 

 scientific principles. 



Before describing the nature of my experiments with drainings 

 of dung-heaps, and stating the analytical results obtained in the 

 analyses of this liquid, I may be allowed to offer a few additional 

 experimental proofs in support of some of the opinions advanced 

 in my paper on the changes which farmyard manure undergoes 

 on keeping. In order to obviate frequent reference to this paper, 

 I would observe that, amongst other particulars, I showed that 

 perfectly fresh as well as rotten dung contained but a very trifling 

 amount of free ammonia ; that short dung, when properly fer- 

 mented, contains more nitrogen than long dung ; for which 

 reason, weight for weight, rotten dung is more valuable than 

 fresh. Respecting the loss which farmyard manure sustains 

 under various circumstances, I furnished numerous experiments, 

 which prove that farmyard manure is deteriorated in value when 

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

 kept ; and that the loss in manuring matters which is incurred in 

 this way is not so much due to the volatilization of ammonia as 

 to the removal of ammoniacal salts, soluble nitrogenized organic 

 matters, and soluble mineral matters, by the rain Avhich falls in 

 the period during which the manure is kept. I further showed 

 that well-rotten dung is more readily affected by the deteriorating 

 influence of rain than fresh, and that no advantage appears to 

 result from carrying on the fermentation of dung too far. Finally, 

 I described several experiments, which led me to the conclusion 

 that the worst method of making manure is to produce it by 

 animals kept in open yards, inasmuch as a large proportion of 

 valuable fertilizing matters is thereby wasted in a short time, 

 and suggested, as the most effectual means of preventing loss in 

 fertilizing matters, to cart the manure directly on the field, and 

 to spread it at once, whenever circumstances allow this to be 

 done. 



Since the publication of my former experiments on farmyard 

 manure, T have had an opportunity of examining some sheep- 

 dung in a highly advanced state of decomposition. This exa- 

 mination has brought out strikingly that the richest excrementi- 

 tious matters are greatly deteriorated in value by keeping for an 



VOL. XVIII. I 



