CHAPTEft YIL 



POUDKETTE HUMAN EXCREMENTS. 



Poudrette, nature of ; small amount of the food of plants in it Human excrement 

 its value Construction of the privies in the barracks at Rastadt Calculation, 

 of the amount of corn produced by the excrement collected ; importance to the 

 neighbourhood Its eft'ect not impaired by deodorising with sulphate of iron 

 The excrement of the inhabitants of -towns as manure Its importance. 



"pOUDKETTE, sold as manure, should consist simply 

 -t of the desiccated excrements of man made into a 

 transportable form. This is not the case, however, as 

 most poudrettes contain, in reality, only a comparative- 

 ly small proportion of excrementitious matter. To 

 show this, it will suffice to point out that the poudrette 

 of Montfaucon, which is one of the best sorts, contains 

 28 per cent., that of Dresden from 43 to 56 per cent., 

 that of Frankfort above 50 per cent., of sand. ~No kind 

 of poudrette is ever met with in commerce containing 

 more than 3 per cent, of phosphoric acid, and the same 

 amount of ammonia. The construction of privies in 

 dwelling-houses (at least, in Germany) does not make 

 it practicable to keep out the sweepings and other rub- 

 bish of the house ; besides, when emptying the pits, it 

 is often the practice, after taking out the fluid contents, 

 to throw into the residuary mass some solid porous 

 body, such as brown-coal or turf-dust, to make it drier 

 and more convenient for removal. All additions of the 

 kind, of course, diminish the percentage of effective and 

 available food elements, and increase the costs of trans- 

 port. The privy pits, moreover, are but rarely water- 

 tight, and permit the greater part of the urine and 



