358 ON THE LACTIC FERMENTATION 
to do is to wash the surface of the glans penis thoroughly with a watery solution 
of carbolic acid, r to 40, in which strength it may be applied to the lips of the 
meatus urinarius without causing inconvenient smarting, and having thus 
merely purified the external integument, remove the cotton cap from the orifice 
of the flask and at once apply it to the organ and direct the patient to micturate. 
The purified glans takes the place of the caoutchouc cap, and as the urine enters 
no regurgitation of air is possible. As soon as the act of micturition is completed, 
a freshly carbolized cotton cap is tied over the mouth of the flask, and as surely 
as this process is properly performed, will you have the unboiled urine, together 
with its vesical mucus (which used to be regarded as the special ferment of urine), 
remain for any length of time free from development of bacteria or any other 
organism, and that whether the urine be acid or neutral in reaction.1 
: But suppose we have to deal with a liquid contaminated with organisms, 
like milk obtained from a dairy, we must purify it by heat. For this purpose 
I have always found exposure for an hour to a temperature of about 210° Fahr. 
sufficient.” 
I say 210°, not 212°, which is the boiling-point of water, because the way 
in which we have proceeded is, after introducing the liquid into the purified 
flask, to immerse the vessel, to a higher level than that of the contained liquid, 
in boiling water : and, in consequence of a certain degree of evaporation which 
takes place through the cotton caps which cover the mouth and nozzle of the 
flask, the temperature of the liquid is prevented from ever rising fully to the 
boiling-point. We thus avoid the occurrence of ebullition ; and this is a very 
great advantage, as we get rid of frothing; and, as already stated, the tem- 
* For further details on this subject, see Tvansactions of the Royal Society of Edinburgh, vol. 
XXVli, 1875, pp. 315 et seq. (p. 275 of this volume). 
* In making this statement I proceeded upon a pretty extensive experience with various liquids, 
such as water, Pasteur’s solution, and turnip infusion, as well as milk. In my experiments with the 
last-named liquid, I had obtained it fresh from the cow milked directly into a glass vessel purified with 
carbolic lotion and then rinsed with water, and having filtered it through a fine cloth, exposed it to 
heat with as little delay as possible. But between the time of the meeting of the Society and that of 
going to press, I have found that milk which has been kept for some hours cannot be purified so easily. 
This I am inclined to attribute to the fact that milk, unlike the other liquids referred to, is a hetero- 
geneous fluid containing oily particles in suspension, which tend as time passes to aggregate and coalesce. 
And it is quite conceivable that bacteria enclosed in such oily masses may be protected by them from 
the action of the hot watery liquid, the drops of butter acting as small portions of cheese have been 
found to do by some other observers. For it is a well-established fact that bacteria withstand a much 
higher temperature in the dry state than when acted on directly by hot water. I have also seen reason 
to believe that large numbers of bacteria grouped in masses are more resisting to the action of heat 
than isolated bacteria, as if the circumferential members of such a mass protected the central ones, 
and this circumference may perhaps aid in explaining the point in question. Again, if we consider 
the adventitious particles introduced in the form of dirt from the milkman’s hands, &c., we cannot be 
surprised that difficulty should be experienced even with fresh milk, unless special precautions are taken 
to promote cleanliness. 
