72 



Use of Waste Organic Substances. [may, 



residues, blood, or phosphates, the mixture being known as 

 poudrette. In order to prepare this substance it is obviously 

 necessary to employ the pan system, and as this is not in 

 general favour in England the application of the method here 

 is limited. The pan system is still in vogue in many town 

 districts, and in at least one place poudrette is manufactured. 

 it is in' very good condition, and yields about 8 per cent, of 

 ammonia, 8 per cent, of phosphates, and nearly 3 per cent, of 

 potash ; excellent results have followed the use of 3 to 6 cwt. 

 per acre. 



In the absence of definite experiments on the subject it is 

 difficult to fix a fair value for poudrette, d priori considerations 

 being very apt to lead to fallacies. It is commonly supposed 

 that anything which has passed through the human or animal 

 body must have a higher manurial value than before, but even 

 if this be true for the whole of the excreta it certainly is not 

 the case for the solid portion. The easily attackable parts of 

 the food are taken up by the body and reappear to a great 

 extent in the urine ; the more resistant portions constitute the 

 chief part of the solid excreta. Any method for the agricultural 

 utilization of the faeces is defective if it fails to collect the 

 urine, and the practical difficulties of doing this are probably 

 insurmountable. 



If the quantities of poudrette available ever became consider- 

 able it would be a matter of great interest to compare it as a 

 fertilizer with meat guano and fish guano. 



Similar fertilizers of much lower grade, yielding 2\ per cent, 

 of ammonia and 8 per cent, of phosphate, are occasionally 

 offered in Kent, but their value being low the cost of hand- 

 ling becomes proportionately higher. 



Sewage Sludges. — In most towns there is a sewage system, and 

 the production of poudrette is impossible. Attempts have been 

 made to utilize the sludge deposited from the sewage, but so far 

 as the writer is aware they have resulted in failure. The sewage 

 contains so much water that the soluble available matter is 

 washed out to form a hopelessly dilute solution ; only the in- 

 soluble portion is left in the sludge, and one could hardly expect 

 it to make a useful manure. 



Edward J. Russell. 



