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fœtid gases, has been attested by Dr. Lethe by, the City Officer of Health,
and my experience fully confirms his observations on this point. But it
was to Condy's fluid to which from some successful experiments in my
Laboratory, that I looked for a larger amount of destructive agency.
The decomposition of the components of this deodorizer affords such an
extraordinary volume of available oxygen that it offers the most ready,
cheap, and certain means of burning up impurities. The very facility, however.
with which these changes take place, at present offers obstacles to
its practical application as proposed, but I have reason to believe that this
impediment may yet be overcome; in fact, I am already in possession of
a combination of materials by which Mr, Condy has sought to give a
more lasting action to it.
The operation of charcoal, I believe, is principally exerted on the sulphuretted
hydrogen and sulphide of ammonium existing in the sewer
gases, but the power of nascent oxygen would not rest here. In sewer
emanations there exist offensive compounds which, although as yet they
have defied the scrutiny of the chemist to define,would not resist the pyrogenic
influence of free oxygen. This, therefore, appears to me the
element to which we have a right to look for the most complete results.
Its most appropriate mode of generation remains for future investigation
to determine. I purpose conducting some experiments with pumice stone,
which I am inclined to think may prove a more powerful deodorizer even
than charcoal.
During the several weeks that I have been engaged at the Broadway and
Bridge Road Shafts, I have not been able to detect the slighest smell from
either, whilst the charcoal sieves have been in use, neither can I ascertain
that any persons accustomed to repass them have experienced annoyance.
The delicate test papers used have occasionally shown evidence of the
escape of gases, but after exposure to them for several days have not evidenced
any intensity of character, whereas, when exposed to the same
without the charcoal, they have become rapidly and powerfully affected.
Upon the whole I am convinced that the apparatus suggested by Mr.
Bean and myself, offers the best practical mode of dealing with this
difficult question. Its easy application, and the facility with which it may
be worked, must claim for it a favorable consideration. Mr. Haywood, the
Engineer to the City Commission, in his Report upon the Ventilation of
Sewers, dated Nov. 22, 1858, remarks also that it " will be the cheapest
in adaptation." In the same Report he states it as his opinion, however,
that the use of charcoal sieves will offer considerable impediment to the
currents which now circulate in the sewers, and that probably three or four
ventilators will be required where there is now only one, unless they are
relieved more freely by the house drains and untrapped inlets than at
present.
Dr. Letheby's opinion and experience are in accordance with my own
upon this point, but even should it be found desirable to increase the
outlets, I believe the apparatus now before you may be rendered applicable
to the roadside gullies, and thus render any increase in the number of shafts
unnecessary. The adaptation of a Syphon outlet underneath it, fitted with
a flap to act in case of drought, would effect this object.
Under ordinary circumstances I consider the use of dry charcoal will
always be sufficient in them to counteract the injurious gases, but during
the prevalence of epidemics, or extraordinary hot weather, some
additional deodorizer may be advisable. in connection with this subject
I beg to bring under your notice an Apparatus, suggested by Mr. Love-