306 SOILS AND MANUEES 



considered in this connection. Briefly, the composition 

 depends mainly upon the following conditions: 



1. The composition of the animal excreta. 



2. The kind and quantity of the litter. 



3. The nature and degree of fermentation. 



4. The amount of loss in the process of making. 



THE EXCRETA. 



The Dung. The dung, or solid excrement, consists 

 mainly of the surplus and indigestible portions of the 

 food. It contains also some of the digestive juices and 

 effete membranes of the alimentary tract, but under 

 ordinary conditions, the proportions of these ingredients 

 are too small to sensibly affect the composition of the 

 manure, and for practical purposes they may be ne- 

 glected. 



The composition of the dung is more or less charac- 

 teristic of the kind of animal by which it is produced. 

 The most striking and perhaps the most important differ- 

 ences are in regard to the proportion of water. The 

 dung of horses, it is well known, is much drier and fer- 

 ments more rapidly than that of cows. Horse dung 

 is, for this reason, more suitable for the preparation of 

 hotbeds, and, for manurial purposes, is generally pre- 

 ferred to an equal weight of cow dung. Horse and cow 

 manures can often be obtained from town stables and 

 milk farms respectively, but on an ordinary farm they are 

 not usually kept separate, and the character of the heap 

 depends partly on the proportions in which they are 

 mixed. The quantity of manure produced by pigs and 

 other animals on an ordinary farm, is not usually suffi- 

 cient to affect the composition of the heap to any great 

 extent, but if it formed a large proportion, it certainly 

 would do so. The composition of the dung of common 



