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agency required, but as several disinfectants, I think, might be made
available for the destruction either of part or the whole of the injurious
gases, some slight modification of the details are rendered desirable according:
as one or the other may be found most useful and economical.
The substitution of a series of "Trays" for holding the disinfectant,
instead of the " Cradle" exhibited in the original model, will, I believe,
be found to answer this purpose, or the application of a series of metal
tubes, placed side by side in a vertical position, with perforated bottoms,
through which the air would pass from the sewer, and be sure to come
more perfectly in contact with the deodorizing agent.
" The exceedingly elaborate report lately presented by Dr. Letheby to
the City Commission, renders it unnecessary that I should enter into
many matters of detail, which I bad previously prepared to lay before
you, but you will remember the experiments which I had the pleasure of
shewing in your presence on the 1st of July last, and the remarks I then
made on the nature of sewer products, and on the agents most likely to
be useful for disinfecting them.
" The principal gases usually existing in sewer emanations, have been
found to be sulphuretted hydrogen, sulphide of ammonium, ammonia,
carburetted hydrogen, carbonic acid, nitrogen, &c., with some others, the
exact composition of which are not yet known. The chemical agent
which will destroy or decompose the greater number of these, will, of
course, ceteris paribus, be the most valuable.
" Mr. Bean having been unable as yet to take the necessary steps for
securing the invention, has prevented my conducting any number of
experiments on the public sewers, and the difficulty of manipulating with
an apparatus constructed of wood, so easily influenced by temperature
and moisture, has also tended to limit my practically carrying out the
design. I have, however, conducted numerous experiments in my laboratory
for the purpose of ascertaining the applicability of the principle,
and have every reason to think that, when manufactured with a proper
material, the apparatus will prove eminently successful.
" The chemical agents which have principally engaged my attention at
present have been—
" 1st. Lime mixed with ordinary charcoal, as originally proposed by
Mr. Bean, and exposed to the sewer emanations by means of his
« Cradle."
"The whole of the sulphuretted hydrogen may thus be decomposed,
and. 1 believe, some of the other gases decomposed or absorbed.
" 2ndly. The oxides of iron, mixed with sawdust.
" These agents have been most successfully used in the purification of
coal-gas by the Imperial and other Gas Companies, which suggested to
me the idea that, by the adaptation of a series of trays to the apparatus,
so arranged as to ensure the perfect transmission of the entire sewer air
thvough them, this mixture would form an admirable material for
securing the object.
" 3rd. The Oxides of iron, mixed with coarsely-powdered charcoal.
" The operation of these would be somewhat similar to the preceding.
There is, however, this drawback to the foregoing substances, that
although the sulphuretted hydrogen and sulphide of ammonium would be
totally annihilated, there are other gases arising from the decomposition
of organic matter, which might possibly remain unaffected by them.
The same may be said of chlorine and some others.
" The agents which in the present stage of my inquiries seem to promise
most hope of securing all possible advantages are—