showing that the nitrogen that is lost on this farm is lost for the most part in the form in which it came on to the land, and that mere surface-action (which is relied upon here) is not sufficient to cause the oxidization of the ammonia and organic matters contained in the sewage. At the same time the amount of purification effected was certainly very considerable. 3. Norwood Farm. Samples of sewage and effluent water collected from Norwood Fields on January 5th, 1871. The sewage employed on this farm was very strong, containing as much as 7-42 parts of ammonia in the 100,000. It will be seen that more than two parts of actual ammonia escaped as such in the effluent water, while nearly one fourth of the albuminoid ammonia also escaped unaltered. At the same time a considerable amount of nitrogen was lost as nitrates and nitrites, showing that a certain amount of oxidizing action was going on. Thus there was a considerable loss of nitrogen, both in its original forms and also as nitrates and nitrites. It must be remembered that this sewage was very strong, and that in this, as in the other two cases, the samples were taken under the most disadvantageous conditions during a very severe frost, when growth was at its minimum. The purification is in every case very considerable; but these comparative results speak volumes in favour of underdraining sewage-farms, and of so obliging all the sewage to pass through the soil. Some interesting results were observed as regards the temperature of the sewage and effluent water. At Breton's Farm in the winter the temperature of the sewage was 46° F., that of the effluent water 40° F. = 4°.4 C., a reduction of 5° or 6° only; while at Beddington Farm the temperature of the sewage was 42° F., and that of the effluent water 34° F.=1°.1 C., a reduction of 8°. Thus with percolation through the soil the reduction is during the winter much less than with surface-flow. On the other hand, we have observed that sewage is always cooled (sco Table, Section II.) during the hottest weeks in summer by percolation through the soil, and almost always heated (sometimes considerably so) by a surface-flow during the summer. These results are favourable to percolation through the soil as opposed to mere surface-flow, both in summer and winter. Percolation causes a considerable cooling in the summer, while in winter it does not cool the effluent water so much as surface-flow docs. SECTION II.-Breton's Sewage Farm. Statement of Weekly Quantities of Sewage received on the Farm, of Diluted Sewage pumped on to the Land, and of Effluent Water received therefrom. Statement of Weekly Quantities of Sewage &c. (continued). Proportion Effluent water pumped, 161,600 galls. Day-sewage only received. {Efluent water pumped, 154,900 galls. Day-sewage only received. Effluent water pumped, 119,900 galls. Effluent water pumped, 83,400 galls. thereof. land. town. Quantity of 32. Jan. 15 to 38.5 1.16 1,042,800 45 Not gauged 1,086,400 44 44.5 Not gauged 1,081,100 45 6 days only |