South Norwood. 



higher land on the farm has a somewhat sharp fall, 

 and the sewage is contoured over this part. The 

 same plots are used continuously for from two to 

 four days. The Experiment will be dealt with 

 hereafter. Cropping. — The greater portion of the 

 farm is laid down with rye grass. Mangolds, oats 

 and mint are also grown, part of the crops being sold 

 and part of the rye grass made into hay. 



The sewage is purely domestic, 



Sewa"ge'\ffl7ent ^""^ ^* ^^ screened and settled, 



and Stream, ^ small portion being settled 



without screening. The chief 



Chemical results are: — 



rather weak sewage and a relatively small amount 

 of organic matter per acre of irrigable area. The 

 clayey surface soil is not a very deep one — only 6 in. 

 to 10 in. — but it has been to some extent improved 

 and lightened by the digging in of ashes, and also, 

 of course, by the sewaging which it has received . . . 

 So far as one can draw a conclusion from the analyses 

 of the final and general effluents — which are fewer 

 in number than might have been wished — these 

 effluents were of moderate quality, the land having 

 evidently had rather too much to do in January and 

 November, 1900. This was fully recognised by the 

 authorities, who were at that time extending their 

 bacterial filters. As has been already noted, the 



CHEMICAL ANALYSES (PARTS PER 100,000 BY WEIGHT). 



Sewage.* 



Bffluent.t 

 (5-11 samples.) 



Stream. 

 (1 sample.) 



Total nitrogen 



Ammoniacal nitrogen ... 

 Total organic nitrogen... 



Albuminoid nitrogen ... 



Oxygen absorbed 4 hours at 80 deg. Fahr. . 



Nitric and nitrous nitrogen 



Chlorine (in water supply 1'3) 



Incubator test as judged by smell ... 



Solids in suspension (hourly samples only). 



6-135 

 4-615 

 1-875 



0-815 

 9-555 

 7-66 



21-9 



2-30 



0-87 



0-10 



1-44 



0-39 



87-1 per cent 



purification 



(average) 



84-1 per cent 



purification 



(average) 



75 per cent 



passed 

 (12 samples) 



0-75 



0-64 



3-20 



No smell 



* Approximate averages of seven sets of samples drawn in equal quantities per hour for 24 hours and of four to seven chance samples, 

 t Including three two-field effluents. 



" These effluents varied in appearance, the general 

 effluents evidently containing rather more suspended 

 matter than the others ; but it is only fair to note 

 that when No. 31 (a general effluent) was drawn, 

 the rainfall had largely increased the flow, and there 

 had also been heavy rains previous to the drawing 

 of No. 35, another general effluent. From an 

 excellent looking effluent with a slight brown tinge 

 and only a trace of flocculent matter (No. 180), 

 there were others which were turbid and with 

 appreciable amounts of matter in suspension. The 

 smell, when the samples came to be analysed, varied 

 from fishy to earthy. The few samples which were 

 tested for reaction were alkaline, and they contained 

 a great deal of lime and a good deal of sulphate in 

 solution." (Part II., page 162.) " The South 

 Norwood farm treats a relatively small volume of a 



difflculty of treating sewage by broad irrigation on a 

 clay soil, in which the aggregate effective surface for 

 purification is small, must be greatly added to by 

 sudden and irregular flushes of storm water. It 

 seems also open to question whether it is advisable 

 to continue sewaging one plot of ground for so long 

 a period (from two to four days) as is actually done 

 at South Norwood. It would make an interesting 

 and useful experiment to try (not merely at South 

 Norwood but at other farms also) the separate 

 effects of treating equal quantities of the same 

 sewage on equal areas of gi-ound, but in the first 

 case with more frequently intermittent doses than 

 in the second." (Fart II., pages 163 and 164.) 



The Bacteriological figures may be summarised as 

 on following page. 



" The results, judged as a whole, do not lend 



57 



