ON THK TREATMENT AND UriLIZATIOX OF SEWAGE. 445 



" It is probable that . . . the application of liquid sewage to land would 

 become a source of revenue to towns only under specially favourable circum- 

 stances, and that, in opposition to the opinions which have been somewhat 

 hastily formed in certain cases, it will more frequently entail some amount 

 of expenditure on the towns themselves. At the same time the benefit to 

 land, and the improvement in the condition of rivers, to be realized by the 

 mode of dealing with liquid sewage, can scarcely be matter of doubt or uncer- 

 tainty any longer." 



Of the 200 towns tabulated in the Second Eeport, 19 had recourse to irriga- 

 tion either wholly or partially or in connexion with some precipitation pro- 

 cess ; and in one case, that of Leamington, irrigation was intended, and has 

 since been carried out. 



Owing to the fact that one of its members is the lessee of Breton's Farm, 

 near Eomford, in Essex, the Committee has had the advantage of making 

 continuous investigations of the results of irrigation with this particular farm 

 for the past three years, results which are detailed in the Annual Reports. 

 Special investigations have also been made with the following results : — At 

 the farms at Tunbridgo "Wells, where the sewage is applied to the surface of 

 the land on the Catch-water System, and where under-drainage has not been 

 systematically carried out (the drains which already exist having, in fact, 

 been brought up to the surface to empty into the carriers), the purification of 

 the sewage cannot be said to be satisfactory ; for althougli a considerable 

 dilution with subsoil-water takes place, the water which has passed over the 

 land is still impure, and, moreover, contains scarcely any nitrates, thus 

 showing that very little oxidizing action takes place. 



The same result was found at the Eeigate Parm at Earlswood, where the 

 state of the efiiuent water was still more unsatisfactory ; in fact, in one 

 instance, it was found that sewage which had passed over the fields was 

 actually stronger, except as regards actual ammonia (?'. e. it contained more 

 of the total solids in solution with more nitrogenous organic matters), than it 

 was after passing over only the first of these fields — thus showing that the 

 ground was so saturated with sewage, that any additional sewage passed on 

 to it could " only concentrate itself by evaporation or by solution of matters 

 in the upper layer of the soil." (Eeport III. pp. 181 to 185.) 



These farms were again inspected in the following year. It was found 

 that the efiiuent water was running clear and free from smell. No analyses 

 were, however, made at this time. The crops included oats, beans, and wheat, 

 as weU as meadow-grass and Italian rye-grass, and seemed to be in a satisfac- 

 tory condition; but no general system of subsoil-drainage had been com- 

 menced. A comparison was made in January 1871, during severe frost, of 

 the results obtained in the purification of sewage at the three following 

 farms : — Breton's Farm, near Eomford, Beddiugton Farm, Croydon, and 

 Norwood Farm. It was found that in the latter two cases, where the sewage 

 was passed over the land on the Catch-water System, it was not satisfactorily 

 purified, the nitrogen escaping in the efiiuent water being only partially in 

 the state of nitrates and nitrites ; while in Breton's Farm, where the sewage 

 passes through the soil, the farm being in eflTect a large filtcr-bcd, " (1) oxi- 

 dation goes on in winter as well as in summer, and almost all nitrogen lost is 

 lost in an oxidized and inofi'ensive form, and (2) this loss is very slightly 

 greater in winter with a very strong sewage than in summer with a weaker 

 one ; so that sewaging in the winter would appear to entail no extra loss of 

 manure." 



It was also observed that while in summer sewage is cooled by percola- 



