The City's Ice
STRAIGHT from the north sweeps down the icy blast, cresting the snowy mountain-top, clearing its rugged barriers, and swaying to rhythmic pulsations the pines along the borders of the lake. Day after day the winds bear down increasing burdens of cold. Hour after hour the icecrystals sink deeper and deeper into the depths below. Then, when the leaden skies are bordered with dull northern gold, figures of men advance upon this natural stage, whose background is the majestic mountain, whose wings are forested with white-capped green. The stillness ends as workers, in gay blanket-coats or heavy corduroys, harvest their winter store, cut out huge squares upon the surface of the lake, trace and retrace their steps, moving like living chessmen in steps of knight or queen. The cold wind of the open north congeals the ice. Hot, dust-filled city winds return it to its normal state once more. Whatever the purity of the source, the summer days, when the ice-cars reach the city, see this common food thrust out on dirty platforms through dirty chutes, thrown into wagons which stand open and exposed to the dust of the city street. Nor does delivery at the door end the possibility of contamination. Solid water may turn to liquid water in unclean refrigerators, cool the refreshing drink of car, of office, or of street in positively filthy water-tanks, or become infected by the hand of its server. Make a personal experiment, look at your own refrigerator after a hundred pounds of ice have melted, and see whether or not the compartment is clean.
Few of the topics considered in this series belong more exclusively to the city than this of ice. Food, air, and milk vary the conditions of their supply by the different requirements of the crowded street and the isolated farm. Ice, on the other hand, to-day as always, finds its chief use in the city. The cold cellar or the well still serves the refrigeration purposes of a large portion of rural America. Where ice is used on the farm, it is commonly taken directly from the individual ice-house, where it has had all the benefits which come from storage and few of the disadvantages which come from handling. Farm food, moreover, is not only fresher and in less need of cold storage than the city’s supply, but it may well be possible that the freer life of the country breeds less desire for cooling foods and drinks than does the far greater confinement of our brick-walled existence. Certainly the city’s necessity for refrigeration and for ice is beyond question. Its food, brought from long distances and often unnaturally preserved by storage methods, must be chilled to be healthful. Its children, wearied by the nervous exhaustion of the streets, have a real need of the tinge of attractiveness which cooled viands provide to obtain a sufficient nourishment.
No other nation can compare with the United States in the consumption of ice. Its use in the Orient is chiefly limited to the foreign settlements and the selected upper classes; while in Europe, though it is used for cold storage, its service as a food is relatively small. Even where modern custom and the inroads of American travelers have made its presence an every-day affair abroad, the cooling drink is offered the diner, but not forced upon him. The waiter presents the glass bowl of cracked ice for acceptance or rejection. In America we have no choice. If the carafe is not full of water frozen in its place, the glass of ice-water is surely present at your elbow. Slight indeed is the probability that we can diminish the city’s call for ice, however loud the annual outcry against its use. Granting that the demand is unlikely to subside materially, let us, in order to determine what the situation really is, consider how the purity of ice is affected by its formation, the possibilities of its contamination during harvesting, sale, and use; and the way in which present-day conditions concern the dwellers of the city.
City ice comes from one of two sources : it may be produced naturally in river, lake, or pond, or it may be manufactured artificially by what, for want of a better name, we may call cold-storage methods. The formation of natural ice is, in itself, one of the strangest of the thousand disregarded phenomena of natural life. The basic causes of that example of the craftsmanship of nature known as crystallization, of that property of matter by which solids group themselves in the fairy traceries of the snow, the gleaming facets of the diamond, or the huge pillars of the salt mines, lie deeply hidden. The effects of that craftsmanship we know, and of those effects few are stranger than the selective process which goes on in crystalline formations. Those tiny particles which make up the regularly formed crystals are able to pick and choose their associates, and refuse to accept for the structure of their walls substances unlike themselves. This is a general rule which governs many forms besides the special one under consideration. Crystalline bodies in solution in the foulest liquids crystallize out in a state of purity so great that analytical chemistry constantly takes advantage of this principle to obtain strictly pure materials. Ice-crystals, forming, will build nothing into the icicles save water. The effect of this natural selective power has a close bearing upon our subject.
Every lake or pond is a great bowl holding in solution and suspension many solid particles, such as the tiny bacterial plants which inhabit its depths, the refuse of the shores, and portions of the solid matter of the bottom. When the falling mercury plunges below the freezingpoint, the contents of these huge bowls suffer a sudden change. Tiny six-sided crystals shoot forth upon the surface, join side by side, and take up so much more space than the water from which they come, that the expanded ice is often thrust up upon the banks. If substances like straw, chips, or refuse are floating on or near the surface of the water when the change takes place, such solid bodies will be imbedded, mechanically caught, between the crystals, in the same fashion that a ball is caught between two clasping hands. There is the first possibility of ice-contamination. A considerable amount of light straw and refuse is likely to be floating upon the surface. The greater part of this, good and bad, pure and impure, is entangled in this upper sheet.
Below the surface of the liquid quite another condition holds good. The ground at the sides and bottom is a non-conductor of cold. In consequence, ice can form only at the top, and the solid mass must grow vertically downward from the surface. As the cold increases, the tiny crystals, forcing their way through the water, shoot towards the bottom like icicles on the eaves of a house. Each pointing icy finger, as it pushes its way downward, constantly rejects all other substances besides water, forces floating bacteria and other solids steadily back, builds water and only water into its structure. Since the whole mass is made up of millions of individual crystals, those solids, and only those solids, which are mechanically entangled between these individual crystals appear in the final cake of ice. Such impurities are comparatively few below the topmost crust. In consequence, the greater part of the ice is cleansed by this process. The old theory that “ frozen water purifies itself,” is true so far as crystallization below the surface (notice those three words) is concerned.
Crystallization is not the only mechanical factor which tends to clear ice from impurities. Once the cold lake is covered with its glittering shield, the water below is no longer ruffled by the wind and is practically undisturbed by the changes in weight due to expansion and contraction. Under such circumstances a lake or pond tends to become a still pool in which all floating matter, which is heavier than the liquid in which it rests, is persistently pulled downward, is constantly sinking toward the bottom. To state it in a different form : once the water’s surface is chained in place, the never-resting force of gravity, then unopposed by many resisting forces, such as wind and wave, goes steadily to work to pull the solid matter in suspension away from the upper layers of the liquid into which the ice is extending. The tiny micro-organisms which are responsible for water-borne disease, are slightly heavier than water. They are borne down also. The force of gravity, which drags them down, works with crystallization to free the lower portions of natural ice from its impurities.
The floating matter of the surface does not make all the trouble. Men and horses, passing over the ice in harvesting, track in no small amount of dirt of various kinds. If the ice is harvested from ponds below the snow line, dust-filled winds from neighboring streets may cover it. If it comes from lakes near manufactories, refuse from the plant may be blown out upon it. If snowfalls and slight thaws come, the snow and ice, melting together, produce snow-ice, the white opaque form known to all. Snow is by no means a welcome addition. It holds readily all solids which fall upon it, and, crystalline as it is, falling snow serves as a filter to the air, entangling and enmeshing bacteria and dust as it falls from the heavens to the earth. Snow-ice is to be avoided. The upper crust of ice is dangerous for use.
The conditions mentioned heretofore have been produced by comparatively normal conditions of ice-formation and of harvesting. The ice-dealer has little share in producing them. The dealer, however, can make trouble for the consumer who desires purity by overflowing his ice or by joining thin sheets to form thick cakes. After a few inches of ice have formed, holes are sometimes cut and the water below allowed to flow over the icesheet. When this freezes it forms what is known as “ overflowed ice.” Such ice, of course, simply imprisons any impurities which may be lying on the surface, and, freezing solidly above the surfacelayer, leaves no chance for such mechanical elimination as natural ice obtains. Few methods could be devised which would more surely imprison undesirable solids than this. The second method is even more troublesome than the first. In mild winters, when the ponds where ice is generally cut do not freeze to a sufficient depth to give a satisfactory cake, narrow sheets are sometimes cut and packed together in such a fashion as to give a doubled cake. Under such circumstances two upper layers with their impurities often come together in the centre of the cake and give out their combined dirt when the ice melts.
From filth produced or preserved in some such fashion comes a large part of the mud which fouls your ice-compartment, or leaves a line of black scum in your glass of water. Difficult though it is to bring a direct charge of typhoid infection against these sources, there is a perfectly reasonable probability that many cases of intestinal diseases have originated in such dirty masses. And cleanliness in this respect is directly within the control of the health authorities of the community. Since individual consumers of ice are unlikely to be able to stop the selling of upper-layer, snow, and overflowed ice, the city should keep such ice from reaching the homes of its citizens. Demand that this slight layer, which contains the dirt, be planed off; let the sale of overflowed ice and its like be forbidden by enforced official act; and conditions will rapidly improve. Every consumer recognizes clear ice at a glance. Inspection is no difficult matter.
When we look over our data thus far obtained, we find many hopeful signs. It is true that the free ice of the north has three foes, namely, the foreign matter of its crust, the burden of snow-ice, and the overflowed ice of the dealer; but it is equally true that two cleansing agencies are unceasingly at work, crystallization and the force of gravity. It is within the power of man to use a third, the planing of the ice. The artificial ice of the factory has been much heralded as an advance upon nature. Before passing to a relation of the researches and discoveries which bear upon our problem, suppose we compare the two.
If the ingenious Yankee who first conceived the possibility of sending Wenham ice to tropical lands could return to view the results of his handiwork, he would be amazed indeed to observe the results of the trade begun so many years ago. Once the torrid zone had tasted ice, the development of the artificial supply was inevitable. To-day, the ice machine, its benefits long since extended far beyond the boundaries of the tropics, is used the world over where any deficiency in the supply of natural ice exists. As the problems of artificial ice are closely connected with the processes of manufacture, a word concerning these processes may be of service here.
The making of artificial ice depends on the fact that certain liquids, like ammonia, turn to gases at low temperatures, absorbing heat from everything around. If you had a stoppered bottle of liquid ammonia in a pail of water, and suddenly released the stopper, the liquid would turn to a gas, and the absorption of heat in the process would so chill the surrounding water as to turn it to ice. This is one variety of the many natural changes which absorb heat and chill surrounding bodies. The commonest change of this kind that we know takes place when the ice and salt of the ice-cream freezer takes heat from the liquid in the can and chills it to solid ice-cream. In the case under consideration here, if you have brine around the inner bottle when the liquid ammonia changes to gas instead of water, the brine remains liquid, but is so chilled that it would freeze a glass of water placed within its bounds. This second indirect method of freezing, that is, chilling brine by the ammonia or some like process, and allowing the cooling solution to freeze water, is the one employed in making artificial ice. The water to be frozen may be placed in tanks in the cold brine, or may be allowed to run continuously down a trough, bordered on each side by tubes of cold solution. In the first case, the ice freezes solidly in blocks. In the second, ice is continually formed at the sides, but the liquid never solidifies to the centre. There is always a stream of water flowing between the cakes of ice. One point more: when the cold brine is pumped through pipes to refrigerators and warehouses, a cold-storage system is formed.
Our special interest in the artificial process has mainly to do with its cleanliness, or lack of cleanliness, as related to the methods used by nature. In general, forced freezing compares unfavorably with the natural processes already mentioned. If the water used in such manufacture is ordinary city water, the excellence of the ice will be in direct proportion to the excellence of the water. And the excellence of the water-supply should be strongly insisted upon, for the forces that cleanse natural ice can do but little to free artificial ice from its impurities. Where water is frozen from a continuous stream, gravity has little chance to purify the ice. Where water is frozen in blocks, crystallization does nothing to make the solid better than the liquid. Artificial ice, frozen in a solid block, freezes from the outside in, and remains liquid in the centre to the last. Because of this, any solids present are driven back towards the centre. In the case of natural ice the impurities, driven downward, sink into the water below. In the case of artificial ice, after they have reached the centre, they are frozen solidly into the block. Moreover, this natural freezing inward gathers all the impurities into the centre of the block, thereby making possible all the dangers which come from concentration as opposed to dilution. Several methods have been employed to do away with this difficulty where the water-supply is questionable. One needs special mention, the tapping of the cakes (just after the final solid freezing) in order to remove polluted water. Reliance on any such alternative as this is likely to be dangerous.
Artificial ice made from impure water must always be of dubious purity. Even where distilled water, probably the safest alternative, is used, one precaution should be taken. The stills should not contain lead pipe. The danger of lead-poisoning in ice is quite as great as the peril of similar poisoning in water. One and only one way lies safety, — in freezing pure water delivered through pipes unaffected by water’s dissolving powers. A former custom, now fortunately somewhat gone by, of serving raw oysters in hollowed, melting blocks of ice, succeeded, when the artificial form was used, in laying the food at the one point where whatever infectious material might be present was chiefly gathered.
Closely related to the production of artificial ice is the growing use of cold storage, probably the best method of refrigeration yet discovered. The large markets of our cities depend almost exclusively upon systems which pump chilled brine through stall after stall and shop after shop. In these, the former custom of placing food-supplies in immediate contact with ice is rapidly changing. A number of the new apartment houses have recently provided refrigerators for their tenants, which are cooled by cold-storage systems running out from small central plants; and there would seem to be no reason why the extension of such advantages to whole blocks and streets in crowded quarters might not be practicable. It is a possibility well worth consideration.
Somewhat reversing the normal sequence, we have so far considered ice the final product. We can scarcely pass to the second stage of our argument without a word concerning water, the source from which the product springs. It can hardly be repeated too often that the city’s problem, as it has to do with water, concerns not the liquid itself but the tiny plants which live within its depths; that the possibility of water-borne disease arises from floating micro-organic forms. Bacterial life is lived under widely varying conditions. Even with a common environment, great diversity appears; and the investigator of bacterial populations often finds wide variations in the numbers present in a given area, even where the surrounding conditions seem apparently much the same. Thickly clustered, living masses of organisms may appear on one part of a lake where other portions show only widely scattered individuals and minute colonies. So men may be found crowding together in the masses of London’s huddled slums, and living the widely scattered individualistic life of the African desert. And as human criminals are found far from the haunts of men and in the city street, so the micro-organisms of disease may be found wherever man may spread infection. Yet disease caused by dangerous organisms must always come chiefly from dense micro-organic growths, and heavily infected liquids.
Natural ice offers no very favorable opportunity for the continued life of even crowded bacterial communities. In a preceding paper I have spoken of three things favorable to bacterial existence, — warmth, nourishment, and darkness. Not one of these is present in pond, river, or pool when ice is forming. Light streams through the glasslike coating into the depths beneath. Bitter cold tends to shrivel and destroy plant life. Nourishment is scant in winter waters. The environment in which these tiny bits of animate creation must carry on their struggle for existence seems forbidding in the extreme. Their life must be difficult enough in the cold liquid. How much more difficult it would seem to be when the fragile plants freeze into hard unyielding ice whose expansive force rends iron shells apart and splits the granite rock. No tale of life in Arctic snows could be more fascinating than the story of that microscopic struggle for survival in the bitter chill, observing that struggle simply from the standpoint of the ordinary observer. But its relation has an interest far more immediately personal than this, and one which concerns directly our immediate question. “ Is city ice safe for use ? If not, what can be done towards its betterment ? ” We have already answered some portion of that question in our discussion of ice-formation. The rest of the answer must depend upon the scientific labors of the handful of men who have attacked this problem from its bacteriological standpoint.
In this day of hurrying clamor for reform, when journals leap into the arena thirsting for the blood of modern dragons of corruption one day, and forget the next day that such strange monsters ever existed ; when every conceivable form of legislative regulation is gravely and soberly proposed; it is well to consider what touchstone may be found to give us some foundation for our beliefs, to enable us to act wisely and justly; for wisdom and justice are sometimes difficult to obtain even by legislative decree. It is fortunate that, in our work for the health of the city, we may settle many disputed points once for all by an appeal to the laws of nature as they are demonstrated in the laboratory. Any discussion for or against present-day ice conditions, for example, should rest either upon the records of past researches or the undertaking of new. The labors of the research man should form the basis for the formulation of laws or regulations intended for the betterment of conditions. We cannot afford the time to-day for discussion not based upon experimentation.
An advertising scheme, widely heralded in recent time, portrays the manner in which much of the experimentation on ice has been carried on. Some ingenious press agent, desiring to show the indifference of his particular watches to heat and cold, froze timepieces in blocks of artificial ice. The result of his efforts is evident to any passer-by who notices an eager group pressing their noses against the jeweler’s window and watching hour hand and minute hand moving over the white dials quite without regard to their unaccustomed frozen environment. The watch-manufacturer freezes watches in blocks of ice. The bacteriologists have frozen the bacteria which inhabit water in tubes of ice or, reproducing nature in the laboratory, have frozen purposely infected waters from the top downward.
Less than forty years reach between the two extremes of the quest. The beginning of the work was marked by the publications of two men: of Dr. Nichols, who reported the first recognized iceepidemic, and of Burdon-Sanderson, who discovered that melted ice or snow contained living micro-organic growth. The end may be said to have been reached in the comparatively recent work of Park of New York, of Hill of the Boston Board of Health, and of Sedgwick and Winslow. From first to last, between eighty and ninety students have published papers on the kindred subjects of the epidemiology of ice and the life of the bacteria at low temperatures. Cycle by cycle, those individual researches fall into a series of groups.
The early work of Burdon-Sanderson, of Cohn, of Leidy, of Pohl and Heyroth, like that of several other pioneers, had a single aim, to determine whether or not bacteria could exist in naturally frozen water. In every case, these investigators inoculated sterile media (nourishing liquids or solids which were wholly free from micro-organic life) with natural snow and ice, and then observed the subsequent growth of bacteria. Pohl studied ice from the Neva. Heyroth investigated the supply of Berlin. The Massachusetts State Board of Health in 1889 analyzed two hundred and thirty-eight samples of natural ice; and the supplies of London, of Paris, of Vienna, and of other cities received attention. Bacteria were found in every case. Scofone, on a scientific expedition to Monte Rosa, even found small quantities of bacteria at heights more than seven thousand feet above the surface of the sea. This preliminary cycle of investigation developed the first part of the general thesis. It proved that naturally frozen water could contain living microorganisms. It did not test results by the essential touchstone of quantitative methods. Knowledge of the number of bacteria before and after freezing is the only thing which will give definite answers regarding the persistence of germ-life or the resulting danger from these forms. This information could not be obtained by any single counting of bacteria. Only by many countings of the number present before freezing and of the numbers left after various periods of time spent in the frozen state, could really valuable and decisive results be obtained.
The group of experimenters who took up the work in what might be termed the second cycle did not obtain this necessary numerical knowledge, but, despite this, were able to carry the investigation some distance forward. Instead of working with natural snow and ice, they froze solutions filled with bacteria and submitted them, not only to freezing temperatures, but to degrees of cold far below that of ice. Von Frisch, Pictet and Young, D’Arsonval, Charin, Ravenel, Janowsky, and others, studied the problem by exposing cultures of bacteria to temperatures ranging from 10° to 400° Fahrenheit below the freezing point of water. All proved that bacterial life could exist even when seemingly hardier organisms perished, but each secured his results by the use of bacteria living in rich and nourishing media, a condition vastly different from the normal life of micro-organisms embedded in ice. This fact, that bacteria lived in severe cold when supplied with ample nourishment, told only part of the story. Not only that, but the results of the second cycle of investigation, from which came a more or less general belief that frozen water did nothing to free itself from impurities, were incomplete and unsatisfactory for another vital reason. Strangely enough, this body of investigators had not yet reached the point of testing their results by quantitative numerical work. They still relied on qualitative tests.
Few things are more essential to the city than for its citizens to acquire some measure of the modern scientist’s reliance upon quantitative methods; for despite the fact that in the differentiation between qualitative and quantitative we find a distinction old as the race itself, the average person pays little attention to quantitative results. Qualitative experiment is like aboriginal cooking, where quantities are unconsidered and the prepared food may vary through all degrees from bad to good. Quantitative experiment, with its possibilities of good results, has existed since that moment in the dawn of civilization when primeval woman first measured out her breadstuffs in a stone cup and, trying different quantities, finally reached a definite amount which would serve her as a standard for her later production of good bread. Progress has always passed through what happens to how much happens, from gathering crops at random to the computation of bushels per acre, from the stifling heat and foul air of the old schoolrooms to the proper number of cubic feet of fresh air per individual in the new, from the general fact that cold will not kill entire bacterial populations to the exact numerical part which the cold of ice plays in limiting or partially cutting off the numbers of the micro-organisms present.
Such a change from qualitative to quantitative methods characterizes the third cycle of the researches on ice. Frankland, Pengra, Frankel, and others, had made isolated efforts at obtaining numerical results; but it was left to Dr. Prudden of New York to consider the problem for the first time by the use of careful quantitative methods, used with relation to certain specific micro-organisms of disease. Using an analogy with the study of men, we may say that Prudden’s work marked the point where this research passed from general anthropology to specific criminology. For the first time the purpose of an investigator bore directly upon those germs which are responsible for water-borne disease. Using definite counted numbers of bacteria and observing their endurance, their period of life, under frozen conditions, Prudden determined that many bacteria were killed by freezing, that different species are very differently affected by the cold, that alternate freezing and thawing are likely to be fatal, and that the number killed increases as the length of time in a frozen condition is prolonged.
Prudden’s results, excellent as they were, left much to be desired. There were various possibilities of errata in 1887 when this work was done. Methods of bacteriological work had not reached the degree of excellence afterwards obtained, and the general knowledge of sanitary science had increased enormously during the twelve years which elapsed before Sedgwick and Winslow began their research in the biological laboratories of the Massachusetts Institute of Technology with regard to the “ effect of freezing and other low temperatures upon the viability (the capacity of living) of the bacillus of typhoid fever, with considerations regarding ice as a vehicle of infectious disease.”
In this investigation, for the first time, bacteriological research on ice was concentrated in such a way as to apply directly to the immediate service of man. Although Prudden had used pathogenic germs (the micro-organisms which cause disease), his labors had largely been confined to comparisons of various bacilli. Now, as a student of the criminal classes might specialize on a single branch of his subject, such as forgery, so the present consideration narrowed down to the one chief water-borne disease of the temperate zone, typhoid fever.
Three striking results appeared as the experiment progressed. First, as regards the per cent of micro-organisms which perished as the time of endurance of cold continued. Fifty per cent of the total number died in half an hour. Less than one per cent of the total number survived after fourteen days. Beyond that timelimit, a slow steady reduction continued until either every micro-organism perished, or the numbers of the bacilli were diminished to an apparently irreducible minimum.
In duration of time, then, in the storage that ice receives in the ice-house, to put it more practically, is to be found one of the greatest factors in the elimination of what might be called the internal organic life of ice. We have already considered how crystallization and gravity work towards that end. We shall see in a moment how this research brought the conclusions on that subject to a laboratory basis. Here we have figures which relate directly to the storage factor, to the length of time ice must be stored before its dangerous bacteria die. Practically all the natural ice which comes to the city is stored for weeks or months before use. Time is a great factor in stamping out the micro-organisms of disease. Able as many are to endure low temperatures for brief spaces of time, the greater part of them die under long exposure to the cold.
A second fact appeared upon investigation. Prudden had already noted that the number of bacteria killed by freezing varied with the species, that such tiny organisms as the ironically named bacillus prodigiosus lived their life in their icy world in a different way from the bacillus typhi. Now came the conclusion, that. not only different species of bacteria were differently affected by the same conditions of cold, but also that within the limits of a single species existed distinct races marked by strongly variant powers of resistance. Four separate races which the experimenters named — A, B, C, D — were considered. All were presumably of the same typhoid type. Striking differences, however, appeared between them. Race C succumbed to the cold far more readily than Race B. Races A and D were neither as weak as Race C, nor as strong as B. Similar variations showed in the growth of each individual race, and the conclusion was finally reached that in different races of a single bacterial species the number killed varies with the race. As in the case of man, we can observe the varied resistance which Northerner and Southerner offer against the invasion of cold and heat; as we see the Negro living and flourishing in climates which destroy the white man; so we may see that one alien bacterial stock dies out in an unaccustomed clime where another persists.
Important as are the conclusions arrived at concerning the purifying effect of storage, another part of the research bears peculiarly closely upon the public health — that which regards the “ effects of sedimentation and crystallization during the freezing of typhoid fever bacilli in water.” The work of every early investigator was marked by a common error, — the conditions under which the bacteria were frozen were not the same as those which obtained in the formation of natural ice. The culture tubes were frozen in a solid block, a way in which natural ice never freezes. In this case an attempt was made to copy the work of nature rather than to follow that of previous experimenters along the same line. Heretofore, the purification of the free ice of the lake solidifying under the winter sky had received but little attention from the men who observed bacterial life in the ice tubes of the laboratory. Make one exception, the presence in natural water of multitudes of hostile infusoria, tiniest of scavengers, who may devour forests of microscopic plants which gravity is drawing towards the bottom, and all the natural circumstances surrounding ice formation were reproduced in this research.
This portion of the investigation offers an excellent demonstration of the hypothesis that, if natural phenomena are to be subjected to laboratory examination, natural conditions must be duplicated. Certainly no reference to the necessity for exact duplication of nature’s processes appears in the fairly extensive literature collected for the present article up to the time that the Sedgwick and Winslow research is reached. The way in which the inherent difficulties of this problem were overcome was most ingenious. Placing about ten gallons of sterile water in a carefully jacketed wine cask, the experimenters inoculated the liquid with typhoid bacilli and exposed the cask to temperatures below the freezing point. The jacketing of the sides and bottom of the cask produced a condition similar to that of a natural pond. Cold could enter only at the top. The ice could grow in but one direction, downward. Natural conditions were reproduced, and it was found that the ice contained about one-tenth as many bacteria as inhabited the water below. The tendency of natural ice to purify itself by the aid of gravity and crystallization had been demonstrated under laboratory conditions.
Three conclusions may be drawn from this research. First, one race of a certain pathogenic germ may persist where another dies. Second, whatever the persistence of any race, exposure to long continued cold, such as takes place in the natural storage of ice, cuts the numbers of the bacteria to a very low quantity. Third, crystallization reduces the numbers in nearly as great a proportion as storage. Since crystallization and gravity exclude 90° of the organisms present in any germ body of water, cold and storage combined exclude almost 99°. When these factors are added together, as they ordinarily are, we may reasonably conclude that ice so formed is safe, provided we hold to our original criticism of the topmost layer. There the number of micro-organisms may be so great as to defy the destructive agencies. The common belief that disease-germs may live for months in ordinary clear natural ice seems unfounded, and the emphasis is placed on a new point, the possibility of the contamination of ice through human carriers and unclean resting-places.
Scarcely another article of human consumption receives so much direct handling just before its use as does this food. Milk and water, tea and coffee are poured. Bread, meat, and butter are cut. Bread, probably handled more than any other food on the list, has a hard crust which offers a rather unfavorable lodging-place for germ-life. Ice, on the contrary, washes the hands of every person who handles it, and affords an ever-ready liquid medium for the immediate absorption of the hosts of bacteria which hands may carry. The carelessness of the handlers of ice, their utter disregard of the resting-places where it may receive infection, may be partly due to their lack of realization that ice is a food, as real a food as meat. Whatever the cause, few substances which pass through the digestive processes of man receive such treatment. Its surface contaminated by the passage of men and horses in the cutting, its sides and base fouled by muddied platforms and dirty straw; covered with the filth of black ice-cars and dust-swept freight stations, your cake of ice commonly receives its only cleaning just before it enters the icechest. So far as the ice-man is concerned, this is generally a hasty brush with a time-worn whisk-broom well filled with the dust of the street and blackened with constant use. According to the personal testimony of various ice-men, not even the precaution of a momentary washing beneath the faucet is ordinarily taken. Add to this lack of cleanly control the immediate contamination of the server’s hand who prepares the ice just before meal-time, and you have excellent opportunity for infection. And this infection, contrary to the conditions which prevail with water and milk, will be normally a producer of isolated disease rather than of epidemics. The proper management of house-conditions rests upon the consumer, but there is much that can be done before ice reaches the house.
Few of the city’s necessities possess such possibilities of regulation as the one considered here. Water, springing from a thousand rills, is the bearer in solution and suspension of a great portion of the matter which it meets upon its travels. Only by extraordinary precautions, by complete control of miles of water-shed, or by carefully constructed filters, can it be cleansed. From the moment of its inception to that of its actual use, water must be kept pure and free. Milk, produced in hundreds of isolated dairy farms, small and large, enters the city in a flood, daily renewed, and requiring daily, almost hourly, inspection. Vegetables and other provisions come in by every thoroughfare, by wagon-load and car, by boat and motor.
Sharply contrasted with these are the conditions of the city’s ice. Harvested in great bulk, since small ponds no longer produce paying quantities, a glance at any large-scale topographical map will show the sources of ’supply. Inspection of sources in consequence becomes a matter of long jumps from point to point. Entering the city through centralized freight stations, ice from a distance could invariably be discharged (as it commonly is) at a single distributing point, where single inspectors at each terminal could determine its condition. In the cases where ice comes in by wagon, it must originate in bodies of water close at hand. These are few at best and easy of centralized control. Concealment of unfortunate conditions in a pond open to the eye of every wayfarer is far more difficult than similar concealment inside four walls, just as immunity from the consequences of assault and robbery in the public square is much more of a problem than it is in the back alley. The ice dealer who attempted to overflow his ice, or to join thin cakes in violation of a law, would have no easy task to do it unconvicted. Even if regulation did not extend to the control of the sources, an enforced law requiring the planing off of the topmost layer would do much. Artificial ice-control is made simple because of the fact that the manufacturer must produce his product in accessible central locations, and each city will support but few plants of this type.
Municipal or state control of the ice business is more than practical, then. It is inexpensive. The comparatively small number of individual and corporate icedealers in each city makes the issuance of licenses a very much less complicated matter than the present issuance of permits to peddlers, to milk-men, and to other purveyors of the city’s foods. Inspection of most food-supplies must occur almost hourly. Inspection of ice need be little more than semi-annual. Visual examination of the pond, the ice-house, and the methods of transportation, bacteriological examination of samples at harvesting and shipping times, regulations against the use of snow and overflowed ice, or proper provision for planing, control of artificial ice-factories in respect both to water-supply and to construction, — all those matters could be governed with a minimum of cost as compared with the possible results obtained.
That great example of the individualistic life, our old friend Robinson Crusoe, before he took up a community existence with Friday, drew up, as you will remember, two parallel columns of bad and good. The critic of the city’s health, striving to adjust a balance, may set down the results of his reasoning somewhat as follows: —
All the bacteria of disease are not killed, even by temperatures far below the freezing point of water.
But when the bacteria have to live for long periods in ice, as they commonly do in ice-house storage, they mostly perish.
Snow-ice and upper ice may be filled with surface impurities.
But nature, in crystallizing natural ice, cleanses its lower layers in the process, while gravity helps to pull the various impurities toward the bottom. It is only the top layer which needs cleansing. This cake can be planed off.
There is grave danger of contamination from handling.
That is true and hard to combat. But the remedy for it lies in the awakening of individual interest.
There is pressing need for proper general control of both the natural and the artificial ice-supply.
But there are unusual possibilities of complete control in the dawning recognition of the fact that the citizen must guard himself and his family by the advice and service of trained experts. Many as are the ways in which the state can protect her children, her greatest reliance must always be the education of the individual citizen, the formation of standards of life, and of approachable ideals.