72 A Solution of the Sewage Problem. [January, 



guano " which we have still to notice. During the progress 

 of the experiments at Leeds it was discovered that the 

 " native guano," when made into a powder and mixed with 

 night soil, absorbed all the moisture, thoroughly deodorised 

 it, and rendered it a dry, inoffensive, and inodorous manure, 

 capable of being easily transported without inconvenience. 

 So valuable was this manure found to be that it was easily 

 disposed of at £4 per ton, in quantities of 40 tons at a time. 



From this discovery it followed that the A B C mixture 

 should be employed to precipitate the colouring matters 

 from refuse dye-waters of large dye-works. Some experi- 

 ments were instituted in the laboratory, and the results were 

 so satisfactory .that the adoption of the process would fully 

 answer the requirements of Mr. Stansfeld's bill for preventing 

 the pollution of rivers. 



The writer has thus endeavoured to give an outline of 

 the ABC process of utilising sewage, to state, and to 

 answer, objections to the process. The chief objections 

 may be summarised as follows : — That the " native guano " 

 is of no manurial value ; this statement is untrue in 

 fact. The writer has considered this objection very fully 

 in a letter published some months since, a portion of which 

 may be quoted here. " 'When manurial value is mentioned, 

 a distinction must be made between the value assigned by 

 chemical analysis and by actual experiment on a farm. The 

 former method of valuation is most erroneous, as it only 

 takes into account two constituents, and omits others of 

 equal necessity to the plant life. Chemical analysis would 

 assign scarcely any or no value to such substances as sul- 

 phate of lime, soot, the warp of the Humber, and the mud of 

 the Nile ; whilst, when a chemist does assign a value in 

 money to a guano or a superphosphate, the price he fixes 

 has little or no relation to the actual selling price. Farmers 

 judge of its value by actual trial on their fields. It is in 

 this way they fix the price it is worth their while to pay for 

 the superphosphate, and in the same manner they judge of 

 the value of ' native guano.' My observations at Leamington 

 and the neighbourhood proved satisfactorily to my mind that 

 the ' native guano' made there had a very high manurial value, 

 and the farmers to whom I spoke about it had tested it in 

 too many ways, and were too shrewd judges of such matters 

 to be deceived in ascribing to native guano what was really 

 due to previous manuring." The second objection is that 

 the cost of the manure is more than £3 10s. per ton. In 

 some experimental cases, perhaps, the cost has exceeded 

 this amount per ton ; but in cases where actual work 



