MANURES. 211 



chief difficulty in making a portable manure from sewage 

 may le'said to be the failure to extract the nitrogen, 

 which is the mcst valuable constituent it ccntains. 



The sewage manures made in Egypt form a useful 

 and valuable supplement to the inadequate supply 

 of farm-yard manure at our disposal. Though not 

 actually rich, comparatively speaking, in fertilising ingre- 

 dients, they are much more so than cur ordinary manure, 

 and they contain large quantities of organic matter whose 

 beneficial effects on the soil have already been dealt with. 

 From the large towns, the contents of cess-pits are, as 

 already explained, removed by specially constructed carts 

 to large filter beds, where a portable manure is produced. 

 The food of man having been originally derived from the 

 soil the total loss of fertilising ingredients, owing to the 

 non-return of sewage to the soil, must be great, for it is a 

 very small proportion of the total production which finds 

 its way back to the land again, and the arrangement for 

 the dispO!>ai cf sewage in European countries prevents 

 more than a mere fraction of it from ever being returned 

 to the soil. The annual value of the material carried into 

 the rivers and the sea thus represents an enormous sum. 

 The material removed from European houses in Egyptian 

 cities is very poor, owing to the large quantities of water 

 present, while that obtained from mcsques and dry closets 

 is much richer. The climate is rarticularly favourable 

 for the production of portable manures from sewage on 

 account of the proximity of the desert, the rapid evapo- 

 ration which takes place, and the low price of labour. 

 The great obstacle to the production of a rich manure is 



