time, as Koch says, two hours, then this procedure must also be relegated to the useless for the practicing physician. In truth this is not the case and as my experiments directed especially to this point will show, a considerable lessening of this time may be made.

It must be borne in mind, that every portion of the instrument must receive the action of the most heat and that air pent up in holes, canals, eyes, etc., must be forced out. In water we possess a body, says Soyka 1 in a work of recent appearance, which has the properties, of conducting heat 27 times more rapidly than air, and of direct action on specific organisms in that it causes a swelling and softening of the cell walls and so promotes action of the disinfectant. These properties of water are brought into play and it meets the requirement of filling all unevennesses in the instruments. In the majority of instruments water finds access of itself to canals, etc., and it is sufficient to place these in a simple vessel filled with hot water. When this does not transpire, as in syringes, it is recommended to fill them with water before placing in the bath.

Now comes the question, how long a cooking is necessary? From experiments on our classical test spores, the anthrax, we find that they are killed by boiling water, at a temperature of 100°C. in two minutes. I thought, therefore that a somewhat longer action, say five minutes, would be required for such inaccessable places as holes, eyes, canals, etc., of instruments. Through special experiments I convinced myself that anthrax spores on silk threads brought into these same inaccessable places were killed by a five minutes cooking provided the article be a good conductor of 1. Soyka, To the Theory and Practice of Disinfection, "Berliner Klinische Medicinische Wochenschrift" 1888, No. 15, 16.

We have taken it for granted that during the entire time of cooking the temperature is at 100°C. in the water bath, and the question now arises how is this to be reached?

Koch specifies that in an open water bath the temperature is not alike in all places. Careful measurement shows that the average temperature is 99°C., in the middle of the upper layer only 98.7°--98.8°C. and on the circumference about a tenth lower. If the heat supply is smaller, then the middle of the mass of water at a maximum, is 97.7°C., while the upper layer shows a temperature of only 97°C. I can fully endorse this, but also give the assurance, that if access of cold air is prevented, and the formed steam allowed to escape through only a small opening, a temperature of 100°C. may be reached and maintained in all layers of the water. So it is simply necessary to have a cover, to the water bath for disinfecting.

Now by putting together what we have found out we arrive at the following: That the very resistant infective germs, anthrax spores, that adhere to our instruments, may be destroyed with certainty, by immersion in a well closed water bath for five minutes, with the temperature held at 100°C. i. e. just the heat of boiling water, care only being taken that the depressions, etc., are filled with the fluid.

Our problem now becomes the adaptability for the conditions arising in practice, of what we have as yet proved for the anthrax spores only. The circumstances before us in practice are different from those already considered, in that here the organisms to be destroyed by disinfection are suspended in substances, e. g., pus, blood, etc., which coagulate by the action of higher degrees of heat, so that the micro-organisms are surrounded by an envelope, resistant to the permeation of heat. This factor naturally required attention in later experiments.

So far as the organism itself is concerned we have until now made experiments with a pure culture only, although of a very resistant organism, while in practice the infected substance may be of a most varied mixture, partly composed of spores of equal resistance to anthrax and partly of less resistant bacteria. It must then be primarily shown that our method is capable of killing pus bacteria which may be sticking to instruments. If we prove that anthrax spores, certainly the most resistant of all pathogenic spores, are destroyed, notwithstanding the increased difficulties of practice, then we have the assurance that we are freed from all less resistant organisms, such as those of diphtheria, tubercle, etc.

Next the question should be answered, if instruments soiled with pus bacteria from pure cultures, are cleansed from them by the method given? It is known that these organisms from a pure culture are destroyed in five minutes by boiling water. In our cases now, parts of instruments, little pieces of metals of all sorts, wood, bone, ivory, glass, etc., were sterilized in a dry chamber, and then smeared with pure culture of pus

bacteria, Staphylokokkus Pyogen, Aureus and Albus, Erysipel and Bacteria Pyocyaneus. Thereupon I either layed them directly into the boiling water or I allowed the smeared substances to dry on and then tried the disinfecting experiment. The pieces were brought out of the water bath with sterilized pinchers and transferred to bouillion or gelatine tubes and then placed in a brew oven held at a temperature of 37°C. Notwithsanding some difficulties which had to be overcome, arising from the presence of iron salts, these experiments proved that our method maintained itself.

It is by no means pure culture of known bacteria that we have to deal with in practice, but pus itself, foul and decomposing blood, wound secretion and such that soil the knife and other instruments, and make them a well of ever new infection, carries the destructive material from wound to wound, and therefore demands pressingly, a certain manner for their destruction. Our method then, if it accomplish its purpose, must be capable of disinfecting pus, i. e., to undoubtedly kill all infectious organisms in it. Previously it was by no means proved and certain that this method would do so, for pus as we have already remarked is a substance rich in albumen, which under the influence of higher degrees of heat coagulates and forms firm particles which surround some of the organisms with a mantle that must resist and prolong the entrance of the required temperature. The following experiment will show if in spite of this, boiling water is sufficient to kill the contained bacteria in five minutes. A moderately wide test tube was filled with pus and placed in a water bath so that the mouth reached just

to

above its surface prevent access of water and dilution of the pus. Then the water bath was covered over and the temperature maintained at 100°C. for five minutes. From pus treated in this manner,different amounts, from a particle to 2 c. c., were used to inoculate nourishing gelatine and examined by the plate method. It showed that in every case the pus bacteria were destroyed. In another case anthrax spores were added to fresh pus and treated in the same manner, when the plates showed that the anthrax as well as the pus spores were killed by their five minutes boil.

One might object that the larger amount of the pus, covering the instruments, is disseminated through the entire amount, and that the dilution was not sufficiently disinfected, so that in any layer of water there might be organisms

to act anew as sources of infection for the instruments. The following shows that in all layers the diluted pus was alike disinfected. One hundred c. c. of pus were mixed with 1 liters of water, from this mixture a test plate was made, the remainder boiled five minutes at 100°C. and then gelatine and agar-agar plates inoculated under antiseptic precautions. The result was that on the test plate a large number of germ colonies developed, while on the other plates inoculated from the boiled mixture, scarcely any, some plates remaining entirely sterile,others developed a few colonies evidently from germs that had settled on the plates from the air, while others contained besides these colonies a few spores which were boiled for two hours without killing them, but they were afterwards found to be perfectly harmless by inoculating

animals with them. It is questionable if these resistant organisms were primarily in the pus or whether they were from unclean articles used in bringing it. The necessities of our case has to do only with the killing of infectious germs, and

we have shown that our measures are sufficient to destroy the most resistant of all such, the anthrax spores, and so we consider our problem in this direction answered. That there are bacteria that far exceed the anthrax spores in resistance is well known, and we have seen from recent works in what an extraordinary degree this may appear. But these organisms belong to the nonpathogenic and harmless and as Esmarch has recently shown, do not necessitate a change in our methods. We may therefore hold to our conclusion given above and proved; that five minutes boiling is undoubtedly sufficient. It has been shown that five minutes cooking kills with certainty pus bacteria from pure cultures applied to instruments, and above all, that it destroys pus germs as well as anthrax, mixed in the dried as well as the fresh pus. Now in conclusion, it must be proved if it does the same for pus adhering directly to instruments.

For various reasons it was necessary to scratch particles of coagulated pus from the instruments after their cooking, which was accomplished with a sterilized knife and gelatine plates could be inoculated with these particles. Pus was then mixed with a great quantity of bouillion cultures of the known pus bacteria, and various complicated instruments, as catheters, forceps, toothed pinchers, scissors, etc., were so thor