15
(2) Salting the hides, for which purpose common salt is used in many
places, and especially in the Punjab, while in Bengal and also in
the North-Western Provinces "Khari," which consists of Sodium
Sulphate with a little Magnesium Sulphate and a very small
quantity of Sodium Chloride, is largely used instead of common
salt, although less so than was formerly the case. This last
material has the advantage of being less deliquescent than com-
mon salt, so that the hides dry more quickly, and for this reason
it is pretty certain that hides cured with ordinary salt would
contain the infection a little longer, if anything, than the Khari-
treated ones, and if the former is sufficient to render the skins
inocuous, the latter will have the same effect.
(3) The third process consists in the use of Chunam (lime) which is
rubbed into the skin just as salt is.
The details of these methods differ very slightly in different provinces. Thus,
in Calcutta, the skins are often dried with or without the addition of salt or lime,
then dipped into a bath of salt and lime, and finally dried once more. Another
process is also largely used there at the present time, which consists of placing
skins, which have been dried in the sun without the addition of any ingredient,
in a bath of arsenic and ammonia or soda for a few minutes, and then drying
them again, the arsenic remaining in the skin and protecting it from the
ravages of insects, for which purpose it is used and not as an antiseptic.
Arsenic is also largely used by European dealers in the North-Western Provinces,
but here again the skins are first dried in the sun, so that, if that alone proves
sufficient to prevent all danger of infection, it will not be necessary to test the
action of arsenic on the contagion. In Bombay, nearly all the skins are tanned
after salting or drying, while in Madras they are either tanned straight away
while fresh, or, if they have to be kept more than 24 hours, they are first treated
with lime or salt. Raw hides in this province are dried in the sun. At
Karachi the skins are either dried in the sun for two days or treated with
arsenic and then sun-dried. In the North- Western Provinces, between October
and May, the skins are sun-dried on bamboo frames, while from June to Sep-
tember they are salted, usually with Khari salt from Patna. Those which are
taken from dead animals are sun-dried. In Western Bengal they are either
sun-dried or treated with Khari, while in Lower Bengal the latter process is
largely used.
It will then be evident that, in order to ascertain whether there is any
danger of rinderpest being carried about India or to other countries through
the export of the hides of animals that have died of rinderpest, it will be
necessary to find out how long the infection remains in the hides of animals,
that have died of this disease, when they are either dried in the sun or shade, or
treated with salt or lime, and with this object in view the following experi-
ments were made.
30. Methods of carrying out the experiments.—As hides are well
washed to free them from blood, after all adherent muscle has been carefully
removed, and even the infection of blood, which contains the contagion of the
disease in the largest quantity, is soon destroyed by complete drying, it is
unlikely that the surface of dried skins would carry the infection of the disease;
but nevertheless in the interior of them the contagion might possibly live for
some time in the blood vessels within the skin, and under favourable circum-
stances might cause infection. Again, the disease is usually conveyed through
the nostrils or mouth of the animal, by infectious substances coming into
contact with them, but the disease can be conveyed with still greater certainty
by the introduction of the virus under the skin. It was, therefore, decided to
make an extract of the small pieces cut out of the skins in sterilised physiological
salt solution (one which contains the same amount of salt as the blood), and to
inject this beneath the skin of a susceptible animal,—a most severe test, and
one which if it failed to produce the disease may be safely taken as evidence
that there is no living contagion remaining in the skins so tested, and hence
they could under no circumstances convey the disease. Skins were also
placed in the feeding troughs of animals and were licked by them, which would
be the ordinary way in which the disease might possibly be communicated
if the skins were infectious. As in consequence of other important experi-
ments that were going on at the same time, we could not afford to run
any risk of infecting our healthy sheds, the earlier experiments had to be