448 REPORT— 1873. 



The general results were : — 



Sewage from the town 416,787 tons. 



Effluent water returned to the tanks .... 52,466 „ 



Therefore Diluted sewage 469,253 



Of which, Amount utilized 385,291 



Amount merely filtered 83,962 





As to the composition of the sewage and effluent water, the average amount 

 of nitrogen for 100,000 tons in the diluted sewage pumped was 5-529 tons ; 

 that in the effluent water 1-147. 



As the total amoimt of diluted sewage was . . . 380,277 tons, 

 And the total effluent water 195,536 „ 



it follows that " the proportion of nitrogen escaping in the effluent water to 

 the total quantity applied is therefore -1067, or about one tenth." 



An estimate was also made of the amount of nitrogen recovered in the 

 crops ; the general result of the whole being that of 100 parts of nitrogen in 

 the sewage pumped, 42 were recovered in the crops, 11 lost in the effluent 

 water, and 47 not accounted for — that is to say, remaining in the soil or esca- 

 ping into deeper subsoil-waters. (See accompanying Report.) 



Some experiments were also made with the view of inquiring into the pos- 

 sibility of the distribution of entozoic disease by means of sewage-irrigation. 

 Some " slime and mud " from the bottom and sides of carriers at Earlswood 

 Farm was examined by Mr. M. C. Cooke, who found that it contained life of 

 various kinds, especially Annelida, but did not detect any entozoic larvae. 

 The existence of this slime at the bottom of the carriers here was attributed 

 by the Committee " to the fact that the subsoil is kept in a saturated condition 

 by the want of underdraiuing ; " and they were of opinion " that when land is 

 thus saturated with sewage, certain atmospheric conditions exist which may be 

 attended by malaria more or less injurious to health." (lloport III. p. 182.) 

 Dr. Cobbold was requested by the Committee to examine, in conjunction 

 with Professor Marshall and the writer, the carcass of an ox fed for two years 

 on sewage-grown grass. It was found to be, as he reports, free from internal 

 parasites of any kind. All the viscera, together with portions of numerous 

 muscles, " with their associated areolar and aponeurotic coverings," were 

 carefully examined. He observed that the conditions were favourable to this 

 result, inasmuch as (1) the grass &c. was ciit and cari-ied, and the animal was 

 not grazed on the farm ; (2) the soil is very porous ; (3) mollusca, so often the 

 intermediary bearers of cntozoal larvce, were scarce ; (4) the only mollusks 

 found (a species of Limncea) contained no cercarian larvaa ; (5) the " flaky 

 vegetable tufts '' collected from the sides of the furrows contained " numerous 

 active free Nematodes, but no ova of any true entozoon ; (6) the sewage pro- 

 bably contained sufficient alcohol to destroy the larvae. The Committee agreed 

 with all these observations except the last. 



The absence of mollusca is most remarkable, and with it must be associ- 

 ated the observations recorded by the Committee of the destruction of wire- 

 worms &c. by the sewage. Thus a crop of American oats was seriously 

 damaged and in danger of being destroyed by the ravages of the Oscinis vas- 

 tator, one of the smallest but most destructive of those grubs and wireworms 

 which at times cause such injury to cereal crops in this country. Two heavy 

 dressings of sewage were applied to this bed daring two successive days, the 

 result being that the grubs were entirely destroyed and the greater part of 

 the crop saved. (Report II, p. 65.) 



