3. Notwithstanding the variety of stink-traps to which you have given trial, and notwithstanding the fact (recorded by your Committee of Health on the Surveyor’s authority) that ‘there does not exist within your jurisdiction a single gully which is untrapped,’ there continue to be frequent complaints of offensive exhalations from the sewers. The mechanical difficulties in this matter of trapping have appeared to be, from the nature of the case, almost insuperable. It may, indeed, easily be conceived, how incompatible are the common uses of a gully-hole with such fineness of adjustment and delicacy of balance as would render the apparatus air-tight from within, and effectually preclude an escape of the gaseous contents of a sewer. Under such circumstances, your Hon. Court has desired that I should express my opinion, how far a different course might be adopted in respect of these exhalations; how far, namely, they might be neutralised within the sewers; how far it might be chemically feasible, and in a sanitary point of view expedient, that a systematic use should be made of deodorising agents; so that any gas escaping from the sewers should at least be divested of its original smell. On this subject, I would submit to you the following considerations. As respects its feasibility (putting aside as foreign to my province all questions of the expense, and all details of the daily arrangement) a first and obvious objection is this: Granted in the abstract, that sewer-gases can be converted by appropriate agents into inodorous compounds; in the practical application of these agents, you would find impediments with which you are already familiar. Theoretically, there may be no difficulty in providing air-tight traps; practically there is said to be every difficulty. Just as that mechanical problem has defeated you in practice, so would the chemical one; and for the same reason. The fulfilment of either problem is a matter of nice adjustment. In proportion as your gully-hole is exquisitely trapped, it becomes liable to obstruction; it loses its use as an inlet to the sewer, nearly in the same measure as it becomes an effective obstacle to regurgitant gases. Similarly, in proportion as these alleged deodorisers might succeed in completely stifling the characteristic odour of sewage, they would be liable to diffuse perfumes peculiarly their own, and to establish, in the vicinity of gully-holes, the alternation of a new nuisance with the old. To proportion with accuracy the introduction of these chlorinous preparations to the amount of refuse traversing the sewers--an amount varying most considerably at different hours of the day, seems to me quite a visionary hope. Failing such accurate proportions, I am not prepared to say that the result would be useful; and I accordingly consider the scheme as not chemically feasible.