VIII.] MANURES DERIVED FROM NIGHT SOIL 245 



in a very short time, the faecal solids, paper, etc., are so 

 completely broken down by bacterial decay that the 

 soil can be spread upon the land and used for growing 

 crops. 



In some towns attempts have been made to manu- 

 facture a concentrated fertiliser by collecting human 

 excreta without any admixture and evaporating off the 

 water, sometimes with the addition of a little acid to 

 fix the ammonia arising from the urea, sometimes with 

 powdered turf, etc., to give the finished material a 

 better mechanical texture. In Rochdale, one of the towns 

 where such a system prevails, the houses are provided 

 with external pan closets and the faeces are collected 

 at short intervals for conveyance to the manure works. 

 The following analysis shows the composition of the 

 resulting manure — 



The almost universal prevalence of a water-borne 

 system of dealing with excreta puts an end to all such 

 systems and intensifies the difficulty of saving the 

 fertilising constituents of human food for the land 

 again, because of the enormously increased dilution 

 they have experienced ; the sewage from towns with 

 water-closets only contains on the average about 2-2 

 parts of nitrogen per 100,000. Where the conditions 

 are favourable and the community has at hand a 

 sufficient area of light, permeable land which can be 

 cheaply graded and adapted to irrigation, then the 

 sewage waters, either with or without a preliminary 



