DISINFECTANTS.

BY F. C. ROBINSON, CONSULTING CHEMIST MAINE STATE BOARD OF HEALTH.

Infection and Contagion.-It may seem a waste of time to define the word infection, but my experience in teaching has convinced me that one cannot begin too far back in giving instruction. Even those who have considerable knowledge of a subject like to hear over again the fundamentals of it, and those to whom it is new and who would understand it, ought to have it developed from the very foundation.

To disinfect is the opposite of infect, and to infect is literally to "make in," or, by usage, to cause a harmful substance to go into an individual, or more broadly, into a place or thing. Thus, not only a man, but a house or clothing or water or a soil may be infected. The word infection as now used is practically synonymous with contagion, although dictionaries still try to distinguish them. Contagion literally means harmful, disease-producing matter, coming by contact. It is a more definite word than infection. Increased knowledge has tended to bring the words together. It was once believed that certain well-known diseases were communicated by touch or contact with the sick man or his clothing or the things he had touched, while others were spread by some miasm or vapor. The former were called contagious, the latter infectious. But the more we know, the more it is apparent that the idea of miasms as disease producers is largely incorrect. There is in most, if not all, such cases, a touch of some kind. In many cases, this touch proves to be that of some lower animal, as rats in the case of plague, and mosquitoes in case of yellow fever and malaria. Infection is thus proving to be contagion and will doubtless more and more prove to be in the future.

All this has broadened to a like degree the matter of disinfection, and also made it more definite. We no longer light fires in the streets of a city where contagious disease is prevalent, in order to destroy the miasm, but select something which will kill the thing with the fatal touch, whether it be a naked germ, so to speak, or the same clothed with and carried by a rat or mosquito. Thus to destroy insects and vermin is now an important branch of disinfection, and undoubtedly the general use of the fly and mosquito screens for doors and windows is a most important step in preventive medicine. Thus, for our present purpose, it is not important to distinguish sharply between infection and contagion. Both represent conditions which must be reached frequently by disinfection.

Disinfection and Deodorization.-But there are two other words frequently confounded which should be sharply separated. They are disinfection and deodorization. Disinfection, as has been said, is to destroy infection and prevent contagion. But somehow the idea is quite fixed in many minds that

infectious matter has an offensive odor; hence, anything which will destroy such odors has been, and still is, quite largely accepted as a disinfectant. How often do we hear the expression made by those who have visited some unclean locality, "Why, you could just smell the infection!" In some chronicles of great plagues, as that of London, mention is generally made of a peculiar prevalent odor everywhere detected, and attributed to the plague miasm. Of course, where deaths were so frequent and corpses not properly taken care of, there must have been odors, but neither plague bacillus nor the bacilli of other infectious diseases have characteristic odors. It is a case of imagination due to the miasm idea, which locates the source of deadly miasms in unclean and foul-smelling places. The imagination has a powerful influence on the senses. To those who consider a lightning stroke as of infernal origin, the odor of ozone commonly perceived about such places is identified as a "smell of sulphur."

I do not wish to decry deodorants. They are proper and necessary, and health officers should know what they are and how to use them, but they are frequently not disinfectants at all, and their use may give an air of security which is false and misleading.

Infection and Filth.-The fact is, an infected place, like a dirty individual, may have a ravishing odor. I would not say one word which might be construed as tending to change the ideas generally prevalent among intelligent people as to the evils which follow from filthy surroundings. But the fact is that there is no scientific evidence that filth itself is the direct source of the infectious diseases which health officers are called upon most often to fight. Neither are bad odors such causes.

On the other hand, moist decaying matter exerts quite a disinfecting power. Very many of the disease-producing bacilli are soon destroyed if put into sewage; and all bacteriologists know that the best culture medium upon which to grow such bacilli is that which is clean and fresh and sweet. It is a basal fact that the human as well as the domestic animal flourishes best in clean surroundings. The reason that, when contagion gets into families living in unclean conditions, it generally stays longer and is more deadly, is due to the secondary rather than the primary action of filth. These secondary actions are lowered vitality, lack of care, and re-infection. Animal parasites, rats, mosquitoes, flies, fleas, etc., breed more abundantly in filthy places, and, as has been said, these are now seen to be of prime importance in the spread of many diseases. Thus when we hear the claim made that because filth does not produce the bacilli of infectious diseases therefore it is not necessary to destroy it around dwelling houses, we must give no heed to such a misleading statement. Upon health officers, concerning all filth, are put the same kind of commands as upon the children of Israel when they were about to enter the promised land. They were forbidden to make any compromise with the people living there by which any of them were to be spared. They must destroy them "root and branch," or named and unnamed woes would be upon them. And we are told that such woes did follow individual cases of disobedience to the divine command. But they followed

no more surely than trouble will to-day if health officers compromise with filth, and deodorize instead of disinfect and destroy it. Theories of just how its acts are more profitably discussed after abating the nuisance.

Room Disinfection-General Principles.-But this is a school of instruction and you want details of how to act, especially. I suppose the disinfection problems which come for solution most commonly are:First, room disinfection.

Second, books.

Third, that of persons.

Fourth, that of animal quarters, pens, etc.

As to the first, I imagine that, in spite of the "coming back" into favor of sulphur to a certain extent, formaldehyde solution is most generally used. Its great practical superiority to all other gases for the purpose is its general harmlessness to persons and things. But if I may judge other states by Maine, it is frequently used very inefficiently. It is hard to eradicate the old idea even among intelligent physicians that a strong smell of a disinfectant is a sure sign that enough has been used. It was for a long time believed by the medical profession that the odor of chloride of lime or carbolic acid has a sterilizing influence. Then again, I suppose that persons not physicians think of disinfectants as poisons, and knowing how small an amount of a poison is deadly, they think that only a small amount of a disinfectant is needed to poison the germs of disease. These things taken with the additional fact that, as a rule, no community or individual wants to pay adequately for the time and materials used in a thorough disinfection, conspire to limit the process to the smallest possible performance which will not cause dissatisfaction. Even conscientious men feel obliged at times to do things in a way they don't fully approve.

The fact is that no amount of simple fumigation with formaldehyde is adequate to disinfect in a great many cases. For it must be remembered that it is a surface disinfectant and does not penetrate deeply into clothing or other articles. It does not act to sterilize masses of sputum which have much thickness, and such masses are doubtless common.

In spite of laboratory experiments to the contrary, I do not believe it safe to use less than a pint of forty per cent solution of formaldehyde to 1,000 cubic feet of room space to get surface disinfection of sufficient completeness; and this accompanied by an atmosphere three fourths saturated with water vapor.

Even though laboratory experiments show that a less amount will sterilize cultures of all test objects, we must not forget two things, first, that house conditions are not laboratory conditions, and secondly, that chemical action depends upon the masses of the reacting substances as well as their nature; that is, that actions which may take place when small masses are used are not always identical with those when large masses are in question. This fact was again brought out in certain experiments made by a German who showed that a so-called "loop culture" of a test bacillus might be killed by a disinfectant of a certain strength, but when

a larger amount of the culture was put with the disinfectant, it was not sterilized. It is well in using disinfectants to use the same principle used by financiers in estimating profits or expenses. They calculate closely just what they will be and then allow a good margin against themselves for unforeseen circumstances.

Room Disinfection-Details.-I recommend in room disinfection a procedure about like this.

First, fumigate with as little previous disturbance of the articles in the room as possible, merely spreading them out so the gas will come to the outsides of them as fully as may be, and, of course, close all large openings from which the gas might rapidly escape.

Let the gas act from three to six hours, then open, remove bedding, clothing, carpets, rugs, and all articles which might conceal in their depths infected matter, and have them steamed, or, in absence of the power to do that, have them exposed to sunlight and air for some hours, and thoroughly swept and beaten. The previous fumigation has made it safe to remove them, for all surface germs are killed. Of course, one who beats or dusts such articles out of doors should do it in a place where and in a manner such that neither he nor others will get any infection which may possibly be present. This is more easily accomplished in the country than in the city. But every city should have a steam disinfector for the use of its health department. Then after carpets, etc., have been removed, floors should be sprinkled with an eight per cent formaldehyde solution (one of forty per cent with three of water), and other wood work wiped with the same. I never have known of a case of re-infection from a room so treated, and I have had many examples of it when not. Of course, there may be rooms so bare that there is little need of anything but the fumigation, but even of these, the floors and wood work should be treated as described. Of course, the question comes up, What is the need of fumigation if so much other work must be done? The obvious answer is that the gas reaches what the other processes cannot. There is a further advantage also in the washing and wiping, especially in case of the poor and ignorant. They connect cleanliness with disinfection, which is a very important thing to do. I repeat again that there is a very large amount of room disinfection as at present practiced, which acts psychologically if at all; that is, it calms the mind. The reason why re-infection is not more common from such work is probably either the law of chance, or that old principle, "the lame and lazy are always provided for."

How should this fumigation be done? In any way which will vaporize safely the requisite amount in the shortest time. The latter provision is of the greatest importance where an inhabited house is being treated, because it may be necessary for the family to use the rooms very soon. The methods in general use are, spraying the liquid upon sheets hung up in the room, or spraying it into the room directly, or vaporizing the liquid in some sort of boiler, or mixing it with lime or permanganate of potassium and using the heat of the chemical union to vaporize the rest of it.

The latter method has the great advantage of rapidity and undoubtedly shortens the time necessary for the gas to act. Experiments seem to show that by using the permanganate method, a room in favorable conditions may be opened at the end of three hours. Details of the process and its testing were recently published by the Maine State Board of Health and copies can be had for the asking. Briefly, it consists of setting a common "ten quart" pail in the room, adding crystals of potassium permanganate, and quickly withdrawing and closing the door. Six ounces of the crystals are used for one pint of forty per cent formaldehyde. The action is over in a few minutes, and the room filled quickly with the maximum quantity of the gas. There is no possible danger of fire. Common unslaked lime can be used instead of the permanganate, but several pounds of the lime are required and some lime does not act well in consequence of being more or less air-slaked.

If any kind of spraying is used, the spray must be very fine or the evaporation is very slow. The thing I wish only to insist upon is plenty of gas in a short time. I am not pushing any kind of apparatus.

I did not mention under general methods the vaporizing of solid or polymerized formaldehyde, because I have seen no apparatus for doing this which recognized the necessity of considerable water vapor in the room. And there is a necessary condition of this kind which the water present in the ordinary formaldehyde together with that present in the air of New England meets very well. But if the air is dry, water must be provided by boiling some away in the room or letting it evaporate from wet sheets or cloths. Of course, with this precaution, the vapor from enough solid formaldehyde is effective.

The original method of getting the formaldehyde was by forming it direct from wood alcohol in some form of "lamp." There is no objection to this method from the standpoint of disinfection when it fulfils the above conditions as to amount of gas and water.

I would urge upon all who do disinfecting to take all precautions as to themselves spreading infectious matter. They should wear special clothes, or, if possible, one garment fitting closely over their ordinary clothes. Such a precaution has the further value that it is an object lesson to those who observe the process.

As to Sulphur.-Could not sulphur be used instead of formaldehyde, burning it in the room?

That was the old method, and undoubtedly if at least three pounds of sulphur be burned in a close room of about 1,000 cubic feet capacity, and an equal weight of water evaporated, it is comparable with formaldehyde in its effect on disease germs. But it is a difficult and somewhat dangerous process and the fumes destroy or injure very many things present in living rooms. For bare business rooms and ships' holds, it is even preferable to formaldehyde, for it is more poisionous to vermin. Indeed it is much to be desired that something should be discovered as deadly to germs and safe to perishable stuff as formadlehyde, and as deadly to vermin as sulphur