Popular Science Monthly/Volume 55/September 1899/The Milk Supply of Cities
|THE MILK SUPPLY OF CITIES.|
THE ever-growing needs of civilized communities constantly demand new methods. At the time when the streets of Boston may have been the actual cow paths which we are sometimes told they represent, the milk problem did not exist. Every farmer owned his cows, and if some of the people in the small communities did not happen to own a cow there were plenty of these animals in their neighborhood to furnish them with milk. But as our cities have grown the farmer has been pushed back farther and farther into the country, while the demand for milk in the cities has been constantly increasing. The man of the city can no longer call upon his neighbor for milk, but must depend upon some unknown farmer living perhaps many miles away. In England the farmer still lives somewhat close to the city, and as soon as one passes the city limits he begins to find the fields and meadows covered with cows. London and Berlin draw their immense milk supply chiefly from a radius of seventy-five miles. In the United States, however, the farmer does not live so close to the cities, and the demand for milk is even greater than in Europe. Our cities must therefore depend upon a wider range of territory. New York draws its milk from a radius of some three hundred miles. It is easy to see that with such conditions many new problems have arisen. These problems, so far as they concern the obtaining of a sufficient quantity and the transportation and preservation of the milk, have, from a business standpoint, been pretty satisfactorily solved. The milk-supply companies succeed in obtaining a sufficient supply at all seasons of the year, and get it into the city in such a manner that when delivered to the consumer, even though it be forty-eight hours old, it is in tolerably good condition. But it is beginning to appear that the problem, as concerns the consumer, is a somewhat serious one, and that this problem has not yet been solved, nor is it likely to be solved unless the consumer himself takes a direct interest in it.
The problem of the milk supply in the smaller cities is quite different from that of our larger cities. In the smaller cities, even those with populations of one hundred thousand, there may be commonly found a number of milkmen who bring into the city the milk from their own farms and personally distribute it. Such a business is a small one, and the dealer and the producer may be held directly responsible for the quality of the milk. In large cities, however, the business is very different. The individual milk dealer who brings in milk from his own farm has almost disappeared, and his place is supplied by the milk-supply companies that control the product from hundreds of farms and regulate the large part of the milk which the city consumes. These companies send milk trains into the country in all directions, and collect milk from thousands of farms. The milk is brought into the city in cars in which it is cooled by ice. It may be already many hours old when it reaches the city. It is taken from the cars, and the milk from many different sources is mixed in large mixers to insure greater uniformity. It is again packed in ice, and remains thus until the individual dealer is ready to put it into his cart and distribute it through the city to the customer.
As a result of this the customer no longer knows whence his milk comes. If he is a citizen of New York, he may receive milk from his own State, or Connecticut, or Pennsylvania, or New Jersey. It may come from a thrifty farmer, or from a slovenly, filthy farm, or, for all that the consumer knows, it may come in part from a farm where there is a contagious epidemic. There is no method of tracing responsibility, no method of even knowing the source of any lot of milk. One morning we may receive milk from northern New York, and the next from New Jersey. One morning, for all he knows, it may come from a model dairy farm, and the next from the most unhygienic surroundings imaginable.
But this is to a certain extent true of other foods. We can not tell where our flour or meat comes from, or our apples or sugar. Why should we be more disturbed over milk than other foods? Indeed, until recently we have had no especial interest in the milk problem, and have taken milk as it has been offered without question, except as to its being pure milk unadulterated with water. But the rapid discoveries of bacteriology, which have shown milk to be such a good locality for bacterial growth, have been raising some very significant questions. We have been told of the countless millions of bacteria which we have been drinking daily. This has somewhat disturbed us, and no sooner have we become reconciled to this idea than we are told of the great amount of filth that finds its way into milk—two hundred pounds of cow dung being the daily ration of New York city, some one tells us. The matter appears more serious still when we are told by the public press that there are more bacteria in city milk than in city sewage, and are informed of the epidemics of typhoid which are distributed by milk, or of the prevalence of tubercle bacteria in this food product. We become suspicious of the milk supply and hesitate to use this food product or to give it to our children.
Naturally, the people in small communities feel somewhat more at ease in the matter since they know their milk producer and can hold him responsible. But it is questionable whether the milk supply of the large city is not more reliable. The milk supply in the city is handled by organizations, and these, on the whole, are rather more likely to exercise care in the treatment of the milk than are the small dealers. The advantage of handling the matter through companies is well shown in many European cities. In the large cities of England and the continent the milk business is commonly handled by concerns that distribute great quantities daily. Now, many of these companies deal with the subject in a very intelligent manner. They exercise a very considerable control over the individual dairy farms. Some of them keep inspectors traveling constantly among the farms, spending $10,000 to $15,000 yearly in such inspections. They will receive no milk from a farm until after an inspector has visited it and looked into the hygienic conditions of the dairy, even sometimes going so far as to make an analysis of the water used in the dairy. Only after such inspection has been declared favorable is the milk received in the city. These inspections are repeated monthly. The appearance of a contagious disease on the farm is noted at once and the milk no longer received, although still paid for. These companies employ chemists and bacteriologists to study the character of the milk received. They educate their men into their business, and consequently employ more intelligent help than small concerns can. They can furnish a more uniform product than can be expected of smaller dealers. They soon acquire a reputation for their milk, which they are very careful to preserve. Such firms can exercise a much more satisfactory control over the individual farmer than can even public statute, since, with their systems of inspection, it is possible to have an accurate knowledge of the actual conditions under which the milk is produced. It is plainly within the power of firms dealing in large quantities to control the character of its milk more accurately than can small dealers.
Results, too, appear on the whole in favor of the large dealers. In the cities where there is a system of rigid milk inspection it is comparatively seldom that the milk furnished by such companies is found below the standard. This milk is kept up to the standard, and the companies having a chemical laboratory and having milk from many sources can keep the quality of the milk much more uniform than can a dealer whose supply comes from a single farm. The milk inspectors usually find that it is the small dealers that fail to meet the standard. Moreover, it is a fact that where epidemics have been traced to milk it has always been in communities where individual milkmen bring in milk from one or two dairies and distribute it personally. All the epidemics of typhoid that have been definitely traced to milk have been in small communities, and none traced to the milk of large dealers. It is true that it would be difficult or impossible to trace to the milk a typhoid epidemic which might occur in a large city, No one is likely to receive the milk from the same source for two days in succession, and the mixing which the milk receives in the receiving station entirely obliterates the individual source. If there should be some milk brought to the city which contained typhoid bacteria it would be impossible to determine the fact, for such milk, after mixing, would be thoroughly scattered beyond any possibility of following it. We may, then, question somewhat the significance of the fact, but it certainly is true that while serious epidemics have been caused by milk in smaller cities no such instance has occurred in the large cities, or been traced to the milk furnished by companies that handle it in considerable amounts. It would seem that if milk has ever been the cause of such diseases in large cities there ought to have been some evidence of the fact obtained.
It is probable, therefore, that the small community can hardly feel itself any better off in regard to the milk supply than the larger city. It is, of course, easier to trace responsibility for bad milk if we know where it comes from, but it is less likely to be very bad if it comes from a large number of sources and is thoroughly mixed. The milk in the large city is perhaps forty-eight hours old when it is received by the consumer. But it has been kept on ice, has perhaps been filtered, and many of its bacteria may have been killed by the long-continued cold temperature. So far as concerns the bacteria question, our milk which is thus two days old, appears to be actually superior to milk delivered in European cities, which is only a few hours old. The free use of ice in our milk car produces a more favorable result than the more rapid handling which the milk receives in Europe. The milk company controlling a large territory, with great resources at its command, can put into practice rules which even public statute can not enforce, and which the individual farmer will rarely do by himself. One who is acquainted with the methods of handling milk in our cities finds that the companies are each year improving their methods, and that the milk is in most places becoming more reliable. The proper solution of the milk supply for our communities is in the formation of large companies, provided they are managed partly for the benefit of the public and not wholly for money-making.
There is little question that the public has become somewhat suspicious of milk, and that many hesitate to drink it as freely as in earlier years. This suspicion is more pronounced in Europe than in the United States. Upon the continent of Europe the amount of milk which is used raw is really very small, and apparently its use in this condition is destined to cease. The younger generation of physicians are now being taught that raw milk is a dangerous food, and in some countries even the children in the schools are being taught that it is not safe to drink raw milk. Such teaching can have only one result, and that is the reduction in the amount of milk consumed. Much less milk is used in Europe than in this country. It is used for tea or coffee or for cooking, and of course for infant feeding, but for any one to drink milk as we do in this country is certainly a rarity. The suspicion under which milk has been placed has decreased its use.
The dangers which are feared in milk are of course connected with the distribution of disease. Most persons who thus hesitate to use milk have simply a vague fear, without knowing just what is to be feared. When we put together all the facts in our possession we find that there is good reason for believing that milk is sometimes concerned in the distribution of the following well-known diseases and some obscure ones: The first is tuberculosis, which is a disease attacking the cow, and, if located in the mammary gland, may infect the milk with tubercle bacilli, and may subsequently produce the disease in the person who drinks the milk. It should be stated, however, that there is good reason for believing that the danger from this source has been overrated. Second, we have diphtheria, which apparently may also attack the cow. The diphtheria germs may get into the milk from the cow, and they certainly do get into the milk occasionally from secondary sources. Scarlet fever apparently is distributed by milk, though whether this disease may come from the cow or only by secondary contamination of the milk is not yet positively settled. Typhoid fever has in a large number of cases been traced to the milk supply. This disease, however, does not occur in the cow, and the germs always get into the milk from a secondary source, such as water or contact with a person who has the disease. Cholera may be distributed by milk, but this is of course of little importance. Of these disease bacteria, the tubercle bacillus probably never grows in milk, while the typhoid and diphtheria germs do. The most common of all troubles attributed to milk are those somewhat obscure intestinal diseases which attack people especially in the summer months, and are particularly common among children. Prominent among these stands cholera infantum. These latter troubles, according to our present knowledge, are not produced by distinct species of bacteria finding entrance into the body and growing there, as are the other diseases mentioned. They appear to be produced by bacterial poisons which are in the milk. The bacteria—probably several different varieties—grow in the milk and there give rise to certain poisonous products, and these, when taken into the stomach, produce the diarrhœal diseases referred to.
The question of more importance is, however, as to the extent of the danger from such causes. This question is much like the famous one of how large is a piece of chalk. There is danger in everything, even in drinking water and breathing air. Is the danger from milk so great as to suggest that we should give up our habit of drinking milk as they have largely done in Europe, or is this danger so slight that we can well afford to neglect it? We can not avoid all sources of disease even if we would. To do this we should need to shut ourselves up in a box, breathe nothing but sterilized air, drink nothing but sterilized water, and come in contact with no other person, to say nothing of wearing sterilized clothes. Such a method will produce physical weakness rather than vigor. We have learned in the last few years that the proper way of avoiding disease is rather by preparing ourselves to resist it rather than try to avoid all contact with possible disease germs. The question is significant, then, whether the danger from milk is so great that we should use every means of avoiding it; or is it one of the slight dangers which we may best class with the everyday incidents against which our proper guard should be simply vigorous health?
It is impossible to say how great is the liability of contracting disease from milk. Sometimes the subject looms up before us in gigantic proportions. When our papers are describing the occurrence of hundreds of cases of typhoid fever in a city, all traced to a milk supply, the seriousness of the problem is very apparent, and very likely we stop drinking milk for a season. But when, on the other hand, we remember the millions of people that are drinking milk daily without injury, and remember that our forefathers have done the same, we grow graver and begin again our old custom. No one can, indeed, pretend to say how great the danger is. That it is greater than that from drinking water is pretty clear. That it is less than that of riding in the cars is probably equally true. That it is greater in a small community than a large one seems probable, and that there is a greater likelihood of its being serious where the milk comes from a single source than where it passes through the hands of a milk-supply company appears to the author to be quite sure.
In his relation to this problem each person must decide for himself. We do not cease to ride in the cars because there is danger here, nor do the innumerable accidents from bicycling deter us from this pleasure. Ought we to give up milk because of an occasional instance of disease? It might be possible to give advice to use milk freely, looking upon the danger as a slight one and one of the unavoidable dangers of living, but if such advice is given some one will instantly declare it bad advice. It might be possible to advise boiling all milk before drinking, and again some authority would say that this is unnecessary and bad. Personally, the author, though living in a small community, uses raw milk with perfect freedom, but would regard it as unwise to allow young children, especially infants, to use it in this way.
As already stated, the agitation over the milk supply is greater in Europe than in this country. While in England milk is used much as in this country, on the continent really little milk is drunk raw, and there is a growing demand for some means which shall deprive milk of the suspicions attached to it. This demand has been rapidly growing in recent years, and has resulted in the appearance of two new industries. These are the preparation of sterilized and Pasteurized milk. Neither of these industries has as yet developed much in the United States, although in our larger cities beginnings are being made along similar lines.
Sterilized milk has been used for many years. Long ago our doctors learned to recommend, for invalids, that milk should be boiled before drinking. This was done before the matter of its relation to bacteria was understood, and when physicians simply conceived that the boiling rendered the milk more digestible. From being used by invalids it came to be suggested in feeding infants, and then, after the relation of milk to possible disease germs had been understood, the general sterilization of milk was widely recommended. The process of sterilization of milk has not taken much of a hold upon the people of this country as yet, nor has it in England. In continental Europe, especially in northern countries, where the amount of tuberculosis is very large, it has made rapid headway, and now in most of the cities sterilized milk can be bought on the streets just as easily as ordinary milk.
In sterilizing milk as it is done in Europe the destruction of the disease germs is not the only purpose. An object of perhaps equal weight is to produce a milk that will keep. There are many circumstances where it is desirable to carry milk for long distances, and to lay in a supply to last many days or even weeks. Under these circumstances sterilization is resorted to, since it preserves the milk.
There are various methods of sterilizing milk. The simplest, and doubtless the most common, is simply the boiling of the milk. This can easily be done by any one at home, and is, beyond question, very widely resorted to. But where the sterilization is to be performed by a public-supply company, boiling is not satisfactory, since the milk, although it will keep some time, is not indefinitely preserved. The common method used is heating with superheated steam. The milk is placed in bottles of special device, holding about a pint or a quart, and are placed, hundreds at a time, in a large chamber which can be hermetically sealed and then filled with steam under pressure. Here the temperature rises to 102° to 106° G. (216° to 220° F.), and is retained here for some little time. This high heat is supposed to kill all the living bacteria that may be in the milk, even the resisting spores being commonly destroyed. While the milk is still in this apparatus, and before the chamber is opened, the bottles are sealed by a mechanical contrivance and then allowed to cool. After this they are taken out of the sterilizer, and are ready for distribution. The milk thus treated is sometimes pure white, although frequently it has acquired a brownish color, which is not enticing to one accustomed to ordinary milk. Moreover, it has a taste of cooked milk, which is to some people very unpleasant. But when the method is successful the milk contains no living bacteria, and may now be kept indefinitely without further change. It may be shipped to all parts of the world, and whenever opened it will be found still sweet. The process is evidently equivalent to the canning of fruit or meat, only more difficult because the milk commonly contains many resisting spores.
Such sterilized milk can be bought almost anywhere in Europe, and there is undoubtedly a growing demand for it. Where this or other sterilized milk is used it is claimed that very favorable results follow. Careful statistics have been collected as to the number of deaths among infants from diarrhœal diseases, and it is found that in some cities the deaths from infants fed upon raw milk are nearly three times as great as among those fed upon sterilized milk. Of course, no typhoid epidemics can ever be traced to such milk, and in general its use seems to meet with decided favor.
There are, however, some serious objections to this method of treating milk, which have been and probably will continue to be sufficient to prevent its wide extension. The first is that such milk appears to be slightly less digestible than raw milk. Over this matter, however, there has been and still is a great diversity of opinion, and many claim that there is really no difference in the digestibility. It is a matter of comparatively little importance, however, at least for adults and healthy children, for the sterilized milk can be digested, and the slight difference in ease of digestion probably has little significance unless it be for weakly individuals. Secondly, the taste of the sterilized milk is that of boiled milk, and this is rather unpleasant to most people. Probably a majority of our people, if called upon to drink sterilized milk or none at all, would prefer to give it up entirely. This is really an almost insurmountable obstacle to the wide extension of the use of sterilized milk, at least for the present generation. Those who have accustomed themselves to the taste of raw milk will not drink sterilized milk, and, if they do not dare to drink it raw, will not drink it at all. If infants are brought up on sterilized milk the next generation may look upon the matter differently, since the taste can be cultivated.
The third objection to sterilized milk is its cost, which pretty effectually prevents its wide use. Here is probably the real reason why the sterilized-milk industry has not extended more rapidly than it has. The cost of the milk that has been subjected to the treatment above described is considerably above that of ordinary milk, and the size of the pocketbook is commonly a matter outweighing, with most people, even matters of health. When raw milk can be purchased at half the price of sterilized milk, or even for a cent or two less, it will be purchased almost uniformly by the bulk of people, rather than the more expensive sterilized milk. Thus it happens that, in spite of the fact that sterilized milk can be purchased easily in most European cities, the business is not a large one. Probably not one quart of sterilized milk is sold to a hundred quarts of raw milk, even in cities where the business is best developed.
There are some who think that this method of treating milk is soon to be recognized as a necessity, and that it will be shortly regarded as improper to drink raw milk as it is to eat raw pork. But the business has grown rather slowly. Most people prefer to purchase their milk raw at a cheaper price and then boil it themselves, if they do not forget it. There is, moreover, one rather serious criticism that is made against this sterilized milk. Even with the high temperature that is used, it is impossible to be sure that all bacteria spores are destroyed. In most cases they are killed, but occasionally, and indeed not infrequently, a lot of milk will contain resisting spores that the heat does not destroy. These few spores that are left may become serious, far more so than the bacteria in raw milk. After sterilization they begin to grow, and, since this milk is very commonly kept for many days before it is used, these germs have a chance to become very abundant in the milk and to produce profound chemical changes therein, in some cases actually developing poisons. The changes that thus occur may be such as to escape notice with the eye, since they do not curdle the milk, and they may even fail to affect the taste of the milk. Such milk is to all appearances good, and would be given to infants without hesitation. If it did contain the injurious products thus referred to the results would be serious. Some bacteriologists are convinced that not a few cases of serious sickness have been produced in this way. When the milk is used shortly after the sterilization this matter is of no importance, since the bacteria spores grow slowly. But sterilized milk is supposed to keep indefinitely, and is therefore likely to be preserved some time before using, giving abundant opportunity for these spores to grow.
For these several reasons there is developing a different method of dealing with the problem. It is the well-known process of Pasteurization. But although the process has been known for several years, its application to the milk business on a large scale is quite new. Pasteurization consists in heating the milk to a temperature of only about 68° to 85° C. (165° to 185° F.), leaving it at this temperature for a short time, and then rapidly cooling. The length of time required depends upon the temperature used, being, of course, shortest for the higher temperature, but it varies from some two minutes to half an hour. This moderate heat does not necessarily produce the cooked taste nor, as we shall see, does it involve an expense which need raise the price. The temperature, however, is not sufficient to destroy all bacteria, and for this reason is looked upon with disfavor by those who feel that what is needed is an absolute destruction of all bacteria. The Germans, who like to do things thoroughly, do not take readily to Pasteurization, and there are others besides Germans who insist that this treatment does not make the milk safe. But if one is looking for practical possibilities rather than theoretical success, there is perhaps at present more to be said in favor of Pasteurization than sterilization.
Pasteurization is found to be sufficient to destroy all the strictly pathogenic bacteria that are likely to be in milk. The germs of diphtheria and typhoid are killed, and even the tubercle bacillus is rendered innocuous by a few moments at a temperature of 75° C. The resisting spores above mentioned are of course not destroyed, and many other bacteria are left uninjured. But the bacteria which escape the heat are not strictly pathogenic, and do not grow in the body. If they produce any injury to the drinker it is because they grow in the milk and produce injurious chemical products there. They are only dangerous, therefore, after they have had an opportunity to grow in the milk for some time. This opportunity they do have, as we have seen, in sterilized milk, but they do not have the opportunity in Pasteurized milk. Pasteurized milk is not designed for keeping, and those who use it know that while the strictly pathogenic bacteria are killed the milk will not keep. It will remain sweet a little longer than raw milk, but it must be used at once. It must be treated just like fresh milk. Under these conditions the bacteria do not commonly have an opportunity of growing sufficiently to produce their poisonous products before the milk is consumed. Practically, then, these bacteria that resist the moderate heat of Pasteurization are of no serious importance in connection with the healthfulness of milk. Pasteurized milk has been deprived of all its strictly pathogenic bacteria, and the germs still left will commonly have no opportunity to grow very much before the milk is consumed. It is therefore the confident belief of many that Pasteurization is actually a safer method of treating milk than sterilization. Moreover, the results appear to be equally favorable, for Pasteurization is claimed to produce an effect upon diarrhœal diseases equal to that of sterilization.
But the most important argument for Pasteurization seems to be that it is really practical, and can be introduced upon a scale vastly more extended than can sterilized milk. The practice of Pasteurizing milk has doubtless been followed not a little by private families, but from the very outset it has appeared that the proper method of dealing with the matter is to treat the milk at a general distributing center, rather than to depend upon the consumer to do it. Not a few devices have been suggested for accomplishing the purpose satisfactorily and rapidly. The machines invented are planned upon two different principles. In one plan the milk is placed in some large vessel holding many gallons and is here heated, commonly by steam coils. It is allowed to remain here at the desired temperature for twenty minutes to half an hour, and is then cooled. This method is necessarily slow—so slow, indeed, that it is impractical for use where large amounts of milk must be treated rapidly for general distribution. It probably could not be used for the milk supply of a city. The other method is called that of continuous flow. Here the milk is allowed to flow continuously over a heated surface, which brings it quickly to the desired temperature. It is kept hot for only a short time, however, and it then flows over a cooled surface, where the temperature is brought down again and the milk is finally delivered from the machine in a continuous stream of cooled milk. Great objections have been urged against this process, from the fact that it is not thorough. The milk is retained at the high temperature for such a short time that many of the bacteria are not killed. The Pasteurization is decidedly less thorough than by the other method. But here, again, before condemning the process it is necessary to consider its purpose. If it is to destroy all the bacteria, or as large a number of them as is possible, it is of course unsatisfactory. If, however, the purpose is to treat the milk cheaply and rapidly in such a manner as to remove the danger of disease distribution through the milk supply, it would appear that such a method is perhaps satisfactory.
So far as can be determined, this method is efficient in destroying pathogenic bacteria. Its efficiency is of course dependent upon the length of time that the milk is retained at the high temperature, and this can be regulated by the rate of the flow of the milk through the machine. All evidence we have seems to point to the conclusion that a temperature of 75° C, continued for a few minutes only, so far destroys or weakens the pathogenic bacteria which are liable to be found in milk that they need not subsequently be feared as producing disease. Of course, there are pathogenic bacteria that are not destroyed by this temperature, but they are not likely to occur in milk. The germs of typhoid, diphtheria, and tuberculosis are probably rendered harmless by such treatment, and these are the chief pathogenic bacteria of milk. Moreover, the other bacteria are very greatly decreased in numbers, so that the dangers of intestinal troubles are at least much reduced. In hospitals where Pasteurization has been adopted the results are as favorable as with sterilization.
The great value of this plan is, however, that it is practical on a large scale. In Copenhagen it has been in practice for some three years very extensively. In Denmark the amount of tuberculosis among cows is very great, somewhat more than half the animals suffering from this disease. As a result the public milk supply is regarded with more suspicion than in countries where the disease is less. It is everywhere recommended that the milk be always boiled before using, but the bother of treating the milk thus daily makes people unwilling to do it, and it is doubtful whether the practice is as common as the physicians think necessary. Some three years ago a company was organized to meet the public demand for safe milk, and it has adopted plans by which it furnishes Pasteurized milk on a scale as extensive as that of the ordinary milk-supply companies. The company has devised and manufactured two large machines which receive the milk. Pasteurize it, and cool it in a constant stream, and are capable of treating two thousand quarts an hour. The milk received by the company is tested chemically and filtered, and then allowed to pass through one of these large machines. After this it is placed in glass bottles and sealed with the company's seal. The heating is done by steam, and the cooling by brine cooled by an ammonia cooling machine. The greatest care is taken in cleaning and sterilizing the bottles, an enormous chamber some twenty feet long and six feet in diameter being used for a sterilizer. Into this the washed bottles are placed, the chamber hermetically closed, and then superheated steam is turned in upon them. Everything connected with the establishment is conducted with the greatest attention to cleanliness, and upon a very large scale. The bottled milk is subsequently distributed in ordinary milk carts. A bacteriologist is constantly testing the efficiency of the machines by bacteriological examinations of the Pasteurized milk.
The most important feature in this undertaking is that the company furnishes the city with milk at the same price as that furnished by the other companies without Pasteurization, It seems strange that this can be done, for the Pasteurization of course costs something. But the explanation is essentially that heat is cheaper than cold. Because of the subsequent Pasteurization this company does not feel it necessary to demand that the milk should reach them in as cool a condition as is required by the other companies. While their business rivals insist that they shall receive milk not warmer than 4° C, this Pasteurizing company receives it as warm as 10° C, and this saving in the cooling largely pays for the Pasteurization. The mechanical bottling enables them to employ a cheaper grade of help than is necessary when the milk is peddled in carts.
The results of this endeavor to furnish safe milk are in quite decided contrast to those connected with sterilized milk. Sterilized milk has now been on the market for quite a number of years, but, in spite of the fact that it can be readily bought in most cities, the actual business is small. The largest milk-supply company in Europe has a demand for only a few hundred quarts per day. This company in Copenhagen offers to the public a milk which has the taste of fresh milk and which has been so treated as to have all pathogenic bacteria within it destroyed, and at the same time the other bacteria greatly reduced in number. This milk it sells at the same price as ordinary milk. As a result its business has rapidly grown, and instead of supplying a few hundred quarts it sells some thirty thousand daily, and the amount of milk handled is increasing with great rapidity. It probably sells more Pasteurized milk than all the sterilized milk sold in Europe.
It would thus seem that we have here actually a practical method of dealing with the new problem of the milk supply. That it is practical is manifest from the actual results in this institution in Copenhagen. Whether it is regarded as satisfactory will of course depend upon our standpoint. Those that insist that the milk must be freed from all danger, and hence deprived of all bacteria, will not regard this method as satisfactory. But probably every one will recognize that milk thus treated is very much safer than raw milk, and that dangers from typhoid epidemics and tubercolosis are removed, even if they do not admit that intestinal troubles are thus avoided.
There can be little doubt that the method would be successful in our own cities, but its success would depend upon the price at which the milk is sold. If the Pasteurized milk is sold for a price much higher than ordinary milk it will not be a commercial success, for the vast majority of people prefer to save the one or two cents per quart, and run the rather slight risk of trouble from the milk. If it can be sold in our cities, as in Copenhagen, for the same price or a price only slightly higher than that of ordinary milk, it is hardly doubtful that it would soon come into favor, for who would not prefer milk that is safe from disease germs if the price is the same? Already there are a few attempts in this direction in some of our cities, but as yet they are only in the beginning stage. Whether they will develop to a wide extent depends probably almost wholly upon the price at which the milk can be sold.
It would appear, then, that this method of Pasteurization by a central company offers the most hopeful solution of this feature of the problem which is growing with the growth of cities. The milk companies could probably arrange, without great expense, such a plan of Pasteurizing large amounts of milk. This only emphasizes the conclusion, already reached, that the most hopeful method of dealing with the problem in our cities is through properly organized companies that can handle milk on a large scale, and will do it conscientiously, and not wholly from the standpoint of money-making.