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it is considered advisable to divide it. If it is necessary to do this, a
certificate should not be given until the equivalent of two full doses
has been given. If, .however, no undue reaction ensues after the first
fractional dose has been taken, it is advisable to give the full dose at
once on the second occasion, after which a certificate may be given.
16. The privileges attached to inoculation are mentioned in Rule
121. They are not admissible in cases of persons who have recovered
from plague. As a further encouragement the Government have
authorized the grant of three days' extra casual leave on full pay to all
public servants for the purpose of being inoculated. Students attending
Government and aided schools, who undergo inoculation, will be
marked in the registers for not more than three consecutive days as
" under inoculation," and such an entry will be regarded as equivalent
to attendance. No subsistence allowance can be granted to inoculated
persons for the period during which they are incapacitated for work
owing to the operation.
17. The Sanitary Commissioner is in charge of all measures
connected with inoculation and will issue the necessary rules as to the
conduct of the operation, supply of Haffkine's vaccine, inoculation
syringes, etc.
(8) Disinfection.
18. Chemical disinfection ought to be resorted to wherever possible.
Of all measures of disinfection, it is the only one which, when effect-
ively carried out, immediately destroys the infective material present
in a room and renders the room at once practically safe for re-occu-
pation. It is, however, essential that it should be carried out by a
trained agency, and experience shows that where such an agency
cannot be employed, it is better to rely on gradual desiccation rather
than on a process of disinfection which is likely to be incomplete and
ineffective. Imperfect disinfection involves waste of energy and
material, brings discredit on the system by exhibiting unsuccessful
results, and engenders a false sense of security with regard to localities
which have been incompletely disinfected and still contain the living
germs of plague. When a building has been disinfected, care should
be taken to prevent its reinfection by rats.
19. According to present knowledge, perchloride of mercury
and cyllin are the most effective chemical disinfectants. Perchloride
of mercury should be used in a strength of 1 in 1,000, to which
2 per 1,000 of hydrochloric acid and a little aniline blue should be
added. If the owners have no objection, interiors of plague-infected
houses should, as a rule, be treated with Wilkinson's coloured solution
which contains the perchloride in the strength stated above. To
ensure that the chemical is free from impurities, it should be
obtained from the Madras Medical Store depot by submitting indents
through the district medical and sanitary officer and the Surgeon-
General. The perchloride should be issued in the form of a concentrated
solution in acid and clear instructions should be forwarded with
each consignment as to the amount of water to be added. With
a view to securing that the dilutions prescribed should be the solutions
in which the disinfectant shall actually be employed, the capacity
5*