CHAP. VIII.] Measures in the Bombay Presidency and Sind. 245
of lime and permanganate of potassium. If the evidence in favour
of the use of ventilation is considered to be sufficient to justify the
costly and troublesome method of removing the roofs of houses, and if
the good effects of ventilation are admitted to be due to oxidation,
ought not cheap and convenient oxidizing agents such as perman-
ganate of potassium to be used in combating the plague? Unfortu-
nately in the case of cow-dung and mud floors it is not likely to be
practicable to employ sufficient permanganate to produce the effect
desired. It might be possible in better built houses with cement
floors. Permanganate might be used in water suspected of being
infected, such as water used by dhobies for washing infected clothes.
But owing to the risk of insufficient quantities being employed, it
would be most objectionable to put it into the hands of unskilled
workers for ordinary purposes. I have shown above that a mixture
of sulphuric acid permanganate is more active in destroying microbes
than either of these substances used separately. Such a mixture
would have the further advantage of removing smells from dwelling
rooms, such smells being unaffected by corrosive sublimate. But it
must be borne in mind that the sulphuric acid enters into the reac-
tion, and is decomposed with the permanganate. Hence the addi-
tion of permanganate to dilute sulphuric acid may diminish the
durability of the effects of the latter. Strong solutions of perman-
ganate mixed with dilute sulphuric acid slowly decompose with
liberation of ozone. With concentrated sulphuric acid the reaction
is violent."
Disinfection
should be done
twice over.
In view of the fact that the coolies employed in disinfecting work
may not carry out the process thoroughly, Mr. Hankin advises that
wherever practical the room should be disinfected twice over.
Practical rules.
The following are the practical rules for the disinfection of build-
ings which Mr. Hankin derived from his experiments:-
"(1) In the case of corrugated iron latrines, isolated pucca build-
ings, and other pucca buildings in which the work can be
done with safety under intelligent supervision, a layer of
dry grass or other inflammable material, at least two inches
thick, should be laid over the whole of the floor and burnt.
Afterwards the whole of the interior of the building should
be washed out with a solution containing one part in 250
of sulphuric acid.
(2) In the case of dwelling rooms in which there are definite
grounds for believing infection to be present, the whole of
the interior should be first washed with a solution of corro-
sive sublimate of 1 in 1,000 strength to which hydrochloric