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London County Council
EXPERIMENTS ON DISINFECTION.
Report by the Medical Officer presenting joint report by Drs. Klein, Houston and
Gordon on the result of their experiments in connection with the subject of
disinfection.
(Ordered to be printed by the Public Health Committee, 16th January, 1902.)
In accordance with the resolution of the Council of 31st July, 1900, experiments have been
conducted by Drs. Klein, Houston, and Gordon with the object of ascertaining the value of
various disinfectants under the ordinary conditions of their use in dwelling houses. A room in an
unoccupied house in the possession of the Council was in the first instance utilised for the purpose
of testing methods of gaseous disinfection, and later a room of about the same size in the shelter of
the Finsbury Borough Council. Among fluid disinfectants carbolic acid, permanganate of soda
bleaching powder, and corrosive sublimate have been tested. Among gaseous disinfectants formalin
and sulphurous acid gas have been made the subject of experiment, the disinfection in this
branch of the inquiry being supervised by Dr. Newman, medical officer of health of Finsbury,
who has kindly facilitated the carrying out of the work.
Seven microbes have been experimented with, organisms representative of highly resistant
and less resistant pathogenic forms being chosen. Consideration was necessarily given, in making
the selection, to the question of the ease with which the particular microbes employed could be
subsequently identified, but the list includes, it may be noted, the organisms of enteric fever,
diphtheria, cholera, and tuberculosis.
Four different sorts of material, in ordinary practice requiring to be disinfected, namely,
cloth, unvarnished or unpainted wood, linen, and wall paper, were chosen. To them, microbes
distributed in broth, in milk, or in melted gelatine, were liberally applied, and the charged
materials were then exposed to the various disinfectants.
As regards gaseous disinfectants it was found that both formalin and sulphurous acid failed
in the case of wood and cloth charged with spores. The contrast observed between wood and
thick cloth on the one hand, and linen and paper on the other, may probably be explained by the
fact that the microbe-containing mixtures soaked into the materials first named ; the microorganisms
were thus not limited to the surface, whereas, in the case of linen and paper, the
organisms were so limited, and therefore were more exposed. In one experiment even the
little-resistant bacillus typhosus, exposed on wood or cloth, was not destroyed by formalin, but
the reporters raise question as to whether the result was due to some fault in the experiment.
This organism was, however, destroyed under like circumstances bv sulphurous acid. Formalin
vapour, on the other hand, showed to greater advantage than sulphurous acid in the case of tubercular
sputum dried on linen and paper.
As regards fluid disinfectants, corrosive sublimate, 1 in 1,000, with 24 hours' exposure,
destroyed all microbes, including the spores of anthrax and the tubercle bacilli ; carbolic
acid in 5 per cent. solution, with 24 hours' exposure, failed to destroy anthrax spores, but was
efficacious for all others. In the case of Condy's fluid, one teaspoonful to a pint with 24 hours'
exposure gave a negative result; when used in five times that strength it was still practically of
negative value; bleaching powder, generally speaking, only destroyed the less-resistant forms of
microbes, though in the case of anthrax spores on paper and on linen, this material proved more
effective than carbolic acid.
In summary it may be stated that the typhoid bacillus was killed by all the disinfectants
except Condy's fluid and bleaching powder. Condy's fluid gave a negative result in each experiment
and bleaching powder for the disinfection of wood and cloth infected with this organism
failed with 1 hour's exposure but was efficacious on 24 hours' exposure. The bacillus diphtherite
was killed by formalin and sulphur dioxide. The vibrio of cholera was in each experiment
destroyed by all the disinfectants except Condy's fluid and bleaching powder. Condy's
fluid was practically of negative value, and bleaching powder was not always efficacious on 1 hour's
exposure, but was successful with 24 hours. Bacillus pyocyaneus was acted upon
in much the same way. It was killed in each experiment by all except Condy's
fluid and bleaching powder. Staphylococcus aureus was also killed in each experiment by all
except Condy's fluid and bleaching powder. Anthrax spores were only destroyed with certainty
by perchloride of mercury, the other disinfectants either failing on each occasion or being
uncertain, and almost invariably failing when wood and cloth were the materials to be disinfected.
For tubercle bacilli, carbolic acid and perchloride of mercury were the only disinfectants
efficacious on each occasion. Condy's fluid and sulphur dioxide were of negative value and the other
disinfectants unreliable. It is deserving of notice that neither formalin nor sulphur dioxide
were efficacious for the wood or cloth infected with this bacillus.
Shirley F. Murphy,
Medical Officer of Health.
Public Health Department,
8, St. Martin's-place, W.C.,
10th February, 1902.
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