148 



Mr. Harry Grimshaw on the 



24 hours mixed together in a large stoneware vessel, and 

 portions of the whole were taken for analysis. In some 

 cases the day and night samples were kept separate, but 

 the real period of trial, three days, was too short to permit 

 much comparison in this respect. 



The following table gives the results of the analyses : — 



Table IV. 



Results of treatment of Salford sewage with Basic Persulphate of 

 Iron together with lime. Purification from soluble Albumenoid 

 Ammonia. 





Crude Sewage. 



Effluent 



anfiltered. 



Effluent filtered. 



Shaken. 



Settled 

 Alb. Amm. 

 per 100,000. 



Alb. Amm. 

 per 100,000. 



% of purifi- 

 cation. 



Alb. Amm. 

 per 100,000. 



% of purifi- 

 cation. 



June 13 





o-88 



o-66 



21 







„ 14 

 „ 15 



... 



o-6 



o-6 



0-48 

 o'40 



20 



33 







June 19 

 „ 20 

 „ 21 





0*64 

 0-80 

 0-84 



0-36 

 0-36 

 0-38 



43 

 55 

 54 





^3 



The above results are from the day samples of sewage, 

 and with this taken into account show a close agreement 

 with my own figures in Tables 3 and 4. 



Remarks upon the General Results of the Trials. — The 

 most interesting feature is found in the comparison of the 

 results obtained in the small experiments on 100,000 gallons 

 per day, and those obtained when applying the same treat- 

 ment to the whole quantity of sewage, this latter in total 

 amount treated being 85J million gallons in about 8 days. 



The two conditions which in the two experiments were 

 essentially different are : — (1.) In June, 1893, after the long 

 drought of this very exceptional year, the Salford sewage 

 was some 25 per cent, more impure than usual. (2.) The 

 rate of flow over the main tanks of the. Salford sewage 



