AND ITS BEARINGS ON PATHOLOGY 357 
ready to be used again in a pure condition a month or even a year later if 
required, 
Now as to the means of preventing the entrance of dust into the liqueur- 
glass while it is being thus charged. Suppose I were going to charge this glass 
(Q) from this flask (the spout of which is alone given in Fig. 5), containing 
Pasteur’s solution introduced on the 7th of August, yet you observe, remaining 
as pure and clear as when it was first prepared, although it has served for charging 
various liqueur-glasses. I should remove the cotton cap from the nozzle, and 
instantly slip the end of the nozzle into the opening which exists in the centre 
of this half of a substantial india-rubber ball (Rk), 
previously steeped in a strong watery solution of 
carbolic acid. The caoutchouc absorbs carbolic 
acid into its substance, so that, even though dry 
after such steeping, it is powerfully antiseptic. I 
then remove the shade and take off the glass cap, 
and immediately substitute the cap of india-rubber 
on the nozzle of the flask (as shown in the sketch). 
Fluid is now poured in, the flexible caoutchouc 
acting as a hinge during the movements of the 
flask, while the antiseptic cap excludes all living 
organisms ; and the instant the flask is withdrawn 
the glass cap is replaced and the shade put on. 
The hemispherical form of the cap also prevents 
lateral currents of air from depositing dust on the 
drop at the nozzle while it is being moved from one glass to another, and a 
second, a third, or a dozen glasses may be thus charged in succession; and 
experience shows that this mode of procedure is so secure that the liquid will 
remain uncontaminated in such a series of vessels until it dries up through 
atmospheric influence. 
The last point is, How do we get the flask in a pure state with a pure liquid 
in it? The flask itself is purified together with its caps of cotton-wool over 
the mouth and nozzle by being heated in the hot box. And here we have another 
great advantage arising from the uniform temperature of the box sufficient to 
purify cotton without impairing its physical properties. We have, therefore, 
a simple means of securing a pure flask to begin with. 
Next, we wish to introduce into it a pure liquid. There is one organic 
fluid, peculiarly adapted for experiments on this subject, which can be got in 
the pure state with very little difficulty, and that is unboiled urine, provided 
we have a healthy urethra to deal with and a healthy bladder. All we have 
