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ordinary fuel in a furnace, as in Messrs. Frazer's; and 3rd, by superheated
steam, as in Mr. Washington Lyon's.
Each of these methods has its advantages, but none is unaccompanied
by some drawback. A sample apparatus of each kind has been inspected
and carefully examined while in operation by the Special Committee
appointed for the purpose.
A few years ago numerous experiments were made by Dr. Ransome (of
Nottingham), and Dr. Seaton (of London), for the purpose of ascertaining
the singeing point of various textile fabrics. The result of the experiments
showed that almost all materials may be kept at a dry heat of 250° for two
or three hours without risk of damage. Dr. Seaton showed, at a meeting of
the Society of Medical Officers of Health, an hospital blanket which had been
baked at this temperature thirty times, and which was in perfectly good
condition. At a dry heat a little above this (255° or 260°) most fine fabrics
begin to scorch, and, if they are exposed for any length of time, they
rapidly begin to change colour. If, however, super-heated steam be used
instead of heated air, this temperature may be exceeded by ten degrees
without damage. Two hundred and fifty, then, is probably the limit to
which dry heat should be allowed to rise in the oven; but the infected
articles should certainly be exposed to at least this temperature, which
is just sufficient to destroy the poison of Small Pox or Fever. It will
thus be seen that a very few degrees of heat make all the difference
between scorching on the one hand, and inefficiency on the other. Now
this delicate regulation is, with an ordinary furnace, almost impossible,
but it can easily be managed by means of gas; and the self-acting disinfecting
stove of Dr. Eansome answers its purpose, most admirably, as by an
automatic arrangement the gas is turned off when the mercury registers a
certain temperature; in fact, the mercury itself does the regulating ; for
as it rises in a glass tube exposed to the heat of the oven, it gradually
encroaches upon an opening through which the gas passes to the burners,
and shuts off the supply. Inside the oven is another ingenious arrangement
for the prevention of fire. It has occasionally happened that lucifer
matches have been allowed to remain in the pockets of clothing submitted
to disinfection, and that these have become ignited at the necessary
temperature of 250°. Should this at any time happen, the temperature
would thus immediately rise many degrees above 250°; and to provide
against this accident, dampers, suspended by chains, are placed over
both inlet and outlet, and one link of each chain is composed of