Chapter VII: MEDICINE, HYGIENE, ETC.-The Disinfection of the Atmosphere (4)

Now, supposing we make another experiment with the test tube, and instead of boiling we add to its contents a few drops of carbolic acid; we find that decomposition is prevented almost as effectually as by the use of the cotton wool. There are many other substances which act like carbolic acid, and they are known by the common name of antiseptics or antiseptic agents. They all act in the same way; and in such cases as the dressing of wounds it is more easy to use this method of excluding bacteria than by the exclusion of the air or by the use of cotton wool. We have here another object for inquiry--viz., the particular property of these different antiseptics, the property which they possess of preventing decomposition. This knowledge is _very_ ancient indeed. We have the best evidence in the skill of the Egyptians in embalming the dead. These substances are obtained from wood or coal, which once was wood. Those woods which do not contain some antiseptic substance, such as a gum or a resin, will rot and decay. I am not sure that we can give a satisfactory reason for this, but it is certain that all these substances act as antiseptics by destroying the living organisms which are the cause of putrefaction. Some are fragrant oils, as, for example, clove, santal, and thyme; others are fragrant gums, such as gum bezoin and myrrh. A large class are the various kinds of turpentine obtained from pine trees. We obtain carbolic acid from the coal tar largely produced in the manufacture of gas. Both wood tar, well known under the name of creosote, and coal tar are powerful antiseptics. It is easy to understand by what means meat and fish are preserved from decomposition when they have been kept in the smoke of a wood fire. The smoke contains creosote in the form of vapor, and the same effect is produced on the meat or fish by the smoke as if they had been dipped in a solution of tar--with this difference, that they are dried by the smoke, whereas moisture favors decomposition very greatly.

I can show why a fire from which there is much smoke is better than one which burns with a clear flame, by a simple experiment. Here is a piece of gum benzoin, the substance from which Friar's balsam is made. This will burn, if we light it, just as tar burns, and without much smoke or smell. If, instead of burning it, we put some on a spoon and heat it gently, much more smoke is produced, and a fragrant scent is given off. In the same way we can burn spirit of lavender or eau de Cologne, but we get no scent from them in this way, for the burning destroys the scent. This is a very important fact in the disinfection of the air. The less the flame and the larger the quantity of smoke, the greater the effect produced, so far as disinfection is concerned. As air is a vapor, we must use our disinfectants in the form of vapor, so that the one may mix with the other, just as when we are dealing with fluids we must use a fluid disinfectant.

The question that presents itself is this: Can we so diffuse the vapor of an antiseptic like carbolic acid through the air as to destroy the germs which are floating in it, and thus purify it, making it like air which has been filtered through wool, or like that on the top of a lofty mountain? If the smoke of a wood fire seems to act as an antiseptic, and putrefaction is prevented, it seems reasonable to conclude that air could be purified and made antiseptic by some proper and convenient arrangement. Let us endeavor to test this by a few experiments.

Here is a large tube 6 inches across and 2 feet long, fixed just above a small tin vessel in which we can boil water and keep it boiling as long as we please. If we fill the vessel with carbolic acid and water and boil it very gently, the steam which rises will ascend and fill the tube with a vapor which is strong or weak in carbolic acid, according as we put more or less acid in the water. That is to say, we have practically a chimney containing an antiseptic vapor, very much the same thing as the smoke of a wood fire. We must be able to keep the water boiling, for the experiment may have to be continued during several days, and during this time must be neither stronger nor weaker in carbolic acid, neither warmer nor colder than a certain temperature. This chimney must be always at the same heat, and the fire must therefore be kept constantly burning. This is easily accomplished by means of a jet of gas, and by refilling the vessel every 24 hours with the same proportions of carbolic acid and water.

The question arises, how strong must this vapor be in carbolic acid to act as an antiseptic? It is found that 1 part acid to 50 of water is quite sufficient to prevent putrefaction. If we keep this just below boiling point there will be a gentle and constant rising of steam into the cylinder, and we can examine this vapor to see if it is antiseptic. We will take two test tubes half filled with water and put a small piece of beef into each of them and boil each for half a minute. One test tube we will hang up inside the cylinder, so that it is surrounded by carbolic acid vapor. The other we stand up in the air. If the latter is hung in a warm room, decomposition will soon take place in it; will the same thing happen to the other cylinder? For convenience sake we had best put six tubes inside the cylinder, so that we can take one out every day for a week and examine the contents on the field of a microscope. It will be necessary to be very particular as to the temperature to which the tubes are exposed, and the rates of evaporation beneath the cylinder. I may mention that on some of the hottest days of last summer I made some experiments, when the temperature both of the laboratory and inside the cylinder was 75°F. I used test tubes containing boiled potatoes instead of meat, and found that the tube in the air, after 48 hours, abounded not simply with bacteria and other small bodies present in decomposition, but with the large and varied forms of protozoa, while the tube inside the cylinder contained no signs of decomposition whatever. When the room was cold the experiments were not so satisfactory, because in the former case there was very little if any current of air in the cylinder. This leads us to the question, why should we not make the solution of carbolic acid and water, and heat it, letting the steam escape by a small hole, so as to produce a jet? It is a singular fact that for all practical purposes such a steam jet will contain the same proportion of acid to water as did the original solution. The solution can of course be made stronger or weaker till we ascertain the exact proportion which will prevent decomposition.

From this arises naturally the question, what quantity of vapor must be produced in a room in order to kill the bacteria in its atmosphere? If we know the size of the room, shall we be able tell? These questions have not yet been answered, but the experiments which will settle them will be soon made, I have no doubt, and I have indicated the lines upon which they will be made. I have here a boiler of copper into which we can put a mixture, and can get from it a small jet of steam for some hours. A simple experiment will show that no bacteria will exist in that vapor. If I take a test tube containing meat, and boil it while holding the mouth of it in this vapor, after it has cooled we close the mouth with cotton wool, and set it aside in a warm place; after some days we shall find no trace of decomposition, but if the experiment is repeated with water, decomposition will soon show itself. Of course, any strength of carbolic acid can be used at will, and will afford a series of tests.

There are other methods of disinfecting the atmosphere which we cannot consider this evening, such as the very potent one of burning sulphur.

In conclusion, the lecturer remarked that his lecture had been cast into a suggestive form, so as to set his audience thinking over the causes which make the air impure, and how these impurities are to be prevented from becoming deleterious to health.

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A NEW METHOD OF STAINING BACILLUS TUBERCULOSIS.

By T.J. BURRILL, M.D., Champaign, Ill.

Having had considerable experience in the use of the alcoholic solutions of aniline dyes for staining bacteria, and having for some months used solutions in glycerine instead, I have come to much prefer the latter. Evaporation of the solvent is avoided, and in consequence a freedom from vexatious precipitations is secured, and more uniform and reliable results are obtained. There is, moreover, with the alcoholic mixtures a tendency to "creep," or "run," by which one is liable to have stained more than he wishes--fingers, instruments, table, etc.

From these things the glycerine mixtures are practically free, and there are no compensating drawbacks. For staining _Bacillus tuberculosis_ the following is confidently commended as preferable to the materials and methods heretofore in use. Take glycerine, 20 parts; fuchsin, 3 parts; aniline oil, 2 parts; carbolic acid, 2 parts.

The solution is readily and speedily effected, with no danger of precipitation, and can be kept in stock without risk of deterioration. When wanted for use, put about two drops into a watch glass (a small pomatum pot is better) full of water and gently shake or stir. Just here there is some danger of precipitating the coloring matter, but the difficulty is easily avoided by gentle instead of vigorous stirring. After the stain is once dissolved in the water no further trouble occurs; if any evaporation takes place by being left too long, it is the water that goes, not the main solvent. The color should now be a light, translucent red, much too diffuse for writing ink. Put in the smeared cover glass, after passing it a few times through a flame, and leave it, at the ordinary temperature of a comfortable room, half an hour. If, however, quicker results are desired, boil a little water in a test tube and put in about double the above indicated amount of the glycerine mixture, letting it run down the side of the tube, gently shake until absorbed, and pour out the hot liquid into a convenient dish, and at once put in the cover with sputum. Without further attention to the temperature the stain will be effected within two minutes; but the result is not quite so good, especially for permanent mounts, as by the slower process.

After staining put the cover into nitric (or hydrochloric) acid and water, one part to four, until decolorized, say one minute; wash in water and examine, or dry and mount in balsam.

If it is desired to color the ground material, which is not necessary, put on the decolorized and washed glass a drop of aniline blue in glycerine; after one minute wash again in water and proceed as before.

Almost any objective, from one-fourth inch up will show the bacilli if sufficient attention is paid to the illumination.--_Med. Record_.

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CURE FOR HEMORRHOIDS.

"The carbolic acid treatment of hemorrhoids is now receiving considerable attention. Hence the reprint from the _Pittsburgh Medical Journal_, November, 1883, of an article on the subject by Dr. George B. Fundenberg is both timely and interesting. After relating six cases, the author says: "It would serve no useful purpose to increase this list of cases. The large number I have on record all prove that this treatment is safe and effectual. I believe that the great majority of cases can be cured in this manner. Whoever doubts this should give the method a fair trial, for it is only those who have done so, that are entitled to speak upon the question."

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