26
.25 per cent.
125 per cent.
.06 per cent.
'04 per cent.
'02 per cent.
Cyllin. . .
Perchloride ...
...
...
x
x
x
-
x
Attempts to cause complete sterilisation of the surface of cowdung floors by the
use of either disinfectant were without effect. One hour after thorough drenching
with either 1 in 500 perchloride, or 1 in 150 cyllin, innumerable organisms could
be recovered by plating small fragments of the mud.
General properties of cyllin.—Cyllin dissolves very readily in water. It does
not appear to be at all corrosive, nor is it, as judged by its use on dogs, very
poisonous. In its non-coagulative action on albumen it, also differs markedly from
both carbolic and perchloride.
As the coagulative action of disinfectants is one having considerable bearing
upon their efficacy, some experiments were made by adding lcc. of white of egg to
10cc. of different dilutions of disinfectants, gently mixing, and noting the result
after 10 seconds—vide table VIII.
V I I I
.
Dilution.
Cyllin.
Perchloride.
Carbolic.
Time.
1 in 8
...
... No Coagulation
. . . Coarse coagulam
Coagulated
...
... 10 seconds.
1 in 400
...
... Dissolved
Coagulated
...
D o .
Do.
1 in 800
...
Do.
...
...
D o .
Do.
Do.
1 in 1200
Do.
...
...
_
Do.
...
Do.
...
...
Do.
1 in 1600
...
Do.
...
...
Do.
Do.
Do.
A very interesting demonstration of the actions of the different disinfectants
was also made by dropping the unbroken yelk of an egg into beakers containing I
in 500 perchloride, 1 in 20 carbolic acid, 1 in 150 cyllin, respectively. At the end
of an hour the carbolic acid had converted the yelk, except in its central portion,
into an opaque and solid mass, showing that along with its coagulative properties
carbolic acid possesses considerable penetrative power. The perchloride had
whitened the surface of the yelk, but had formed so thin a pellicle of coagulated
material, that the yellow yolk beneath still shone through translucent and mobile.
The yolk in the cyllin was scarcely affected, the only change being a toughening of
the surface membranes - of the yelk.
Conclusions.—The carbolic acid co-efficient of cyllin determined by a
m o d i f i - c a t i o n o f t h e R i d e a l W a l k e r m e t h o d i s , i n t h e c a s e o f b o t h t h e t y p h o i d b a c i l l u s a n d
the staphylococcus pyogenes aureus, 12 . 5. A more delicate indication is given by
using a fixed time and making the dilution the indicator. By this method the
action of cyllin on the typhoid bacillus is about 12 . 5 times that of carbolic, whilst
on the staphylococcus pyogenes aureus it is 8 times that of carbolic. The action
o f
c y l l i n o n t h e o t h e r h a n d . u p o n t h e s t a p h y l o c o c c u s i s o n e - t h i r d a s p o w e r f u l a s
that of perchloride, whilst in the present series of experiments the action of cyllin
on the typhoid bacillus was under one-sixtieth that of perchloride The latter
figure is clearly due to a very exaggerated action of perchloride on the typhoid
culture used which might not be confirmed on other strains, and the figure given
with the staphylococcus pyogenes aureus which would make the carbolic acid
co-efficient of perchloride about 24 is much more likely. I can find no mention of
the carbolic acid co-efficient of perchloride of mercury as worked out by others, but
the co-efficient 24 fits in very well with the strengths of these disinfectants, empiri-
c a l l y e m p l o y e d ,
i . e .
, p e r c h l o r i d e 1 - 1 , 0 0 0 o r 1 - 5 0 0 , c a r b o l i c 1 - 4 0 o r 1 - 2 0 ,t
h e
former being used in a dilution 25 times that of the latter.