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by the Public Health Committee to furnish a report upon the
matter, which I did in the following terms:—
TO THE PUBLIC HEALTH COMMITTEE.
Report on the advantages of steam for the purpose of disinfection,
with special reference to the apparatus known as Thresh's Patent
Current Steam Disinfector.
Gentlemen,
The advantages of steam over dry heat are first the power
it possesses of penetrating into the substance of materials exposed
to its influence to an extent far beyond that possessed by dry heat.
The temperature of it is more rapidly raised, and is uniform
throughout the apparatus. It has been shown that a thermometer
placed in the middle of 16 folds of blanket will register a temperature
exceeding 212 degrees Fahrenheit in 15 minutes in a Steam Disinfector,
the temperature in the chamber being 220 degrees Fahrenheit,
while to obtain a like result in a Hot Air Chamber a temperature of
280 degrees Fahrenheit would have to be reached within the
chamber, and that temperature maintained for two or three hours,
causing discoloration and frequently destruction of the articles
exposed, the heat not being uniform throughout the chamber and
the penetration doubtful.
It has been demonstrated that Bacillus exposed to saturated
steam at a temperature of 212 degrees Fahrenheit for five minutes is
killed although enveloped in 16 folds of blanket, or placed in the
centre of a flock mattress, both of which are non-conductors of heat.
To accomplish the same object by dry heat a temperature of 280
degrees Fahrenheit would have to be maintained for three hours or
more. The full heat is obtained in a steam apparatus in 30 minutes,
while the Dry Heat Oven belonging to the Vestry takes two hours
to register a temperature of 220 degrees Fahrenheit. Great
economy is therefore effected in the consumption of fuel by a steam
apparatus. The Local Government Board are so convinced of the
advantages of Steam over Dry Heat as a Disinfector that they will
only grant loans to Sanitary Authorities for the construction of the
former.
The advantages claimed for the Machines known as Thresh's over
other Steam Disinfectors are: 1st, Its relative prime cost. A
suitable machine can be fixed at the Vestry's station for the sum of
£168, whereas the cost of fixing a Washington Lyon's Machine (the
form of machine mostly hitherto used in England), including the
necessary alterations, has been estimated by your Surveyor at £479,
the cost of the machine alone being £276 10s.