INTERNATIONAL HEALTH EXHIBITION-ABSTXACT OF A LECTURE OX PURE MILK. Dolivered on July 30th, 1884, by G. W. WIGNER, F.I.C., F.C.S. PURE milk is the natura1 food of infants, and in many cases the most appropriate food for invalids, and it may fairly be said to be essential to the growth of a healthy raoe of men and women. But it is even more than this, Milk may be regarded as ti model food, and as a complete food. It is a model food because it is nature’s own food, designed for the sustenance of the young of animals, and, a1 such, it contains and furnishes all the nutritive properties in due proportion required by a pow- ing animal. Milk of comse differs slightly, according to the animal from which it is derived; and this point me shall have again to consider at greater length, but at present we must simply view it as a typically perfect food.It would be hard to give any food a higher recommendation than this, and yet it is not too much to say that two-thirds of the inhabitants of London, or indeed of England, have any practical knowledge of what pure milk is, and that at least one-half of the remainder only consume it occasiondly rather as a luxury than as an article of food. Now milk is not only a perfect food, but it is the most extensively used food. Some might think that this post of honour belongs to bread, lout really I think it mould be the food that, including children with the population, is used more extensively than even bread. Prom pretty careful enquiry, it appears that; the consumption of milk among the middle classes of London, is something like 10 gallons per head per year ; but there are a large proportion of the poor to whom the cost of milk is serious, and there are a large proportion of the rich to whom, I am afraid, milk is less palatable than it should be ; and therefore it would be a very moderate estimate to say that, on the average, 39 gallons per head per year is consumed by the entire population, OF say, 1+ ounces per head per day.Now London has been rendered somewhat notorious by the outq about the amount of the Water Rates ; it will perhaps surpriae some to hear that the amount of the Milk Bill of London is within about 10 per cent. of the amount of the Water Bill of London, and while the water rates amount to about $21,562,000, the milk rates, if so I may call them, amount to S1,400,000 per year, or about 5s.lod. ger head per annum, There is a good deal of difference, however, in the aetual incidence of the miE rate as distinct from the water rate; because the poor, who have but little money to spare, are practically untouched by the water rate, their proportion of the landlord’s tax being almost too small for consideration, while, on the other hand, they are among the largest consumers of milk, and, unfortunately, from the very necessity of their purchases bcling small, say ad. worths, or &d. worths, they buy from the worst vendors, and, without doubt, succeed in procuring the most heavily adulterated milk. Milk consumers have, however, become so habituated to iise the poor watered asd skimmed milk which is supplied by these tradesmen, that the loss which they incur fromTEE ANALYST.175 day to day is not appreciated; and although their infants are deprived of the food which they requiiw, the result shows rather an increase in the bills of mortality than an improvement in the character of the milk supply. Of course milk has been a source of an immense number of cases of prosecution and litigation-persecution the milk dealers call i h b u t anyhow, whether it is persecu- tion or prosecution, for close upon twenty-four yeam-that is ever since the passing of the Act of 1860 for the suppression of adulteration-milk dealers have appeared i n police courts, quarter sessions, and every other mad having power to deal with such matters, not only from week to week and day by day, but many times a day, and yet milk adulteration goes on as fast as ever.Pure milk ought to be such a simple and straightforward term that it should not need definition, but legal sophistry has been exerted to such an extent upon the milk subject, and discussions of every sort have taken place in reference to milk, that even those two words differ in meaning according to the views of the persons by whom they are used. I define pure milk to be the milk produced by a properly fed cow in a state of health. I do not by this mean to imply for a moment that a cow should be fed to the highest pitch which modern science can devise, or that a veterinary surgeon should be kept in constant attendance upon it ; but I do imply, that a man who puts forward his herd of cows as milk-producing machines, and sells the milk which these cows pro- duce to the public 8s genuine milk, is bound to take reasonable precautions to keep them in health, and such proper precautions as any man who values his stock would take, to see that they are sufficiently fed with proper food to prevent their deterioration in health and milk-giving power.There are certain persons in the milk trade who distinctly challenge this view, and I shall not be putting the matter fairly before you if I do not state their arguments from their point of view, even though I: state them merely to show their fallacy. The view which these representatives of a certain section of the milk trade take is, that any liquid which comes from the udder of a cow-no matter how much that cow may have been wrongly fed-is pure milk, and has a right to be classed 8s such, and to be exempt of the penalties of the Adulteration Act.The leading argument which they put forward in favour of this view ia, that the prize beastn of the Agricultural shown have frequently given milk below the usually accepted standard of quality both as regards cream and solids not fat. I admit this fact without hesitation; it is well known, but the reason is not far to seek j animals at these shows are fed in such a way as to force the quantity of milk which they yield to the maximum, while at the same time the animals them- selves are kept as far as possible in the highest external condition, and calcdated to attract the eyes of those who judge of animals by external appearance.When thcse very same cows m e taken back to their homesteads, regularly and properly fed, kept from the impure air of the show-ahed or show-yard, and milked in a propey way, no such abnormal results are obtained, but the milk assumes the ordinary typical character, even when the quantity yielded is somewhat less. Pure milk, therefore, should not merely be the produce of the cow, but should be the produce of the cow in a healthy condition and reasonably well fed, Granting, then,THE ANALYST. - 176 that this definition be accepted, in the first imtance, we have to consider whether it is capable of being formulated in a more distinct way, so that, for inatance, it would be possible for the milkman or analyst, by examining the milk, to say whether the liquid fulfils the conditions I have laid down ; and here I am compelled at once to say, No, it would not be possible ; but the utmost that could be done by science and practical knowledge combined is that a certain limit may be laid down below which pure milk will not fall unless under circumstances of most exceptional character.This limit is in practical use, and is adopted by a very large number of public analysts throughout the kingdom. 1 pass now to consider the different constituents of milk, that is the various different parts into which it can be approximately divided, and into some of which, as a matter of fact, it is divided in the various processes of cream, butter, curd, and cheese making. These different constituents are Water, Fat, Caseine, Albumen, Sugar, and Salts, &c.; and for convenience of demonstrating the fact clearly, I have arranged on the table before me a series of bottles (which Messrs. Welford and Sons, who have the large Dairy in the Southern Gallery, have kindly placed at my disposal), that you may see the proportions of each of these ingredients contained in one gallon of milk. Here, for instance, we have the Water contained in one gallon of milk, which amounts to 81bs. ~oz., and each of the other constituents in its proper relative proportion. I ought at once to disabuse your minds of the idea that milk is absolutely constant in composition; it varies to some considerable extent, but in talking of it to-day, for popular purposes, I shall assume a fair average composition, and explain the extent to which the variations occur afterwards.Commercially we get fat in a state of what may be called (‘semi prity,” as Cream. Good cream contains from 50 to 60 or 65 per cent. of butter fat, the remainder consisting of water and a small proportion of the other constitupnts of milk. When cream is churned into butter the envelopes of the fat globules are broken, and a large number of these tiny little spheres of fat, originally of microscopic size, adhere together, while a large proportion of the water and the soluble constituents are washed away with the butter milk. We thus get butter fat in a still higher state of purity. Good butter, well made and well worked, should contain somewhere about 88 per cent. of pure butter fat, and the highest class of butters will contain rather more than this.To get the butter fat, however, in a state of purity, the butter must be melted with the water, soluble matters and curd separated ; the clear limpid oil, of beautiful amber colour, floats on the top, This, when poured off and allowed to chill, foms pure butter fat. Fat in some form or other is an absolute essential to the dietary. If children aro brought up without the use of buttor, or a butter substitute, they rapidly lose health and condition, and even in many savage races, we find that the fat of animals is con- sumed in large quantities, taking the place of the butter of more civilised countries. Following out this argument, I see no reason why, with proper precautions in its manu- facture, butterine should not be used to a considerable extent, to replace the deficiency of butter, from which we at the present time suffer, Butterine, when properly made,THE ANALYST.I 7 7 is nothing but the best and purest dripping, flavoured with milk, so as to make it resemble butter as much as possible. Tho next constituent of milk that we have to notice is Caseine. This is the flesh- forming constituent of milk, and is called curd. It is classed as one of the most valuable constituents, and is a highly nitrogenous matter. Indeed, with the exception of a small amount of albumen and Lacto Protein, all the nitrogen of milk exists in the form of caseine. Caseine forms the basis of our cheeses of every kind, except the real cream cheese, It will therefore scarcely surprise you to hear that it is highly nutritious.We all know how hard-working men live, to a very great extent, upon cheese with a quantity of bread, and not only do they thrive on the food, but perform an amoqnt of physical work which most of us in this room would be quite incapable of undertaking. It is therefore fair to look upon caseine as being the work-sustaining portion of milk, and to say that if a sample of milk is deficient in caseine, it is deficient in a constituent most necessary for securing health. Albumen constitutes nearly the whole of tho remainder of the nitrogenoua matter in milk. It is difficult to define the exact position which this albumen holdsin the dietetic value of milk. It forms a small proportion, only about one quarter of the nitrogenous matter present, but owing to its more soluble form, and the greater difticulty with which it is coagulated, it appears to me extremely probable that its real food value may be higher than the other nitrogenous constituents.There is some amount of evidence, although not yet a certainty, that this form of albumen is peculiar to milk, and that it differs from the albumen present in eggs, but it seems probable, that like the volatile acida present in the fat of milk, this substance has a special nutritive value of its own, and that without this albumen milk would not be a perfect or complete food. Of course in the case of whey, which is not unfrequently used as a diet, the albu- men forms a vory itnportant part, because the caseine, containing some three-fourths of the nitrogenous matter, has already been separated, and the albumen, with a trace of Lacto Protoin, form the only nitrogenous matter available.Sugar of milk is a very peculiar sugar, differing from most other sugars. Nearly all its properties, both chemical and physical, differ from cane sugar, in not being so sweetening in its properties, and yet it has a pleasant taste, perhaps more agreeable in flavouy than most of the glucoses and other uncrystallizable sugars. Sugar of milk itself, however, is crystallizable, but with a different form of crysta11ieatio.n to cane sugar or beet sugar, and its solution in water behaves differently during concentration, a large proportion of the milk sugar present being deposited at a certain stage of the boiling, in an imperfect crystalline form, while the other part remains in solution.The polarieation diff ers considerably from the polarization of any other known sugar. All these different points mark it out as a peculiar sugar, Them ia a good deal yet to be done in investigating the chemistry of augar of milk, and it appems very probable that at some future time, further investigation may show that in reality what we look upon as a simple sugar, consiists of different substances mixed together in proportions which are at present unknown, Sugar of milk is important in another way2 as it forms the great point of di9erence between human milk and COW’B milk.1 t 8 THE ANALYST. ~~~ ~~ ~ ~ ~~ ~~ ~ Human milk contains a larger proportion of sugar than COW’S milk, and fat, less caseine, albumen, and ash.It is from this that the formula generally adopted in the manufacture of artificial human milk is obtained ; cow’s milk is diluted with water, and then milk sugar added; by this means we obtain a liquid which assimilates somewhat closely in chemical composition to true human milk. MINERAL MATTER. This term includes a variety of salts which, physiologically considered, are of very great importance in the composition of milk. It is absolutely essential for the formation of bone and muscle that a growing child, or for the matter of that an adult, should be supplied with certain phosphatic substances, lime, salts, etc. Milk contains these ingredients in the right proportions to form the bone and muscle of a child. We now come to the water, the last and largest constituent.Water, of course, strictly speaking, has no real dietetic vdue, and yet without water milk itself would be useless as food, because it is essential that the valuable food ingredients of which we have already been speaking should be dissolved or emulsified, so as to be in a suitable form capable of easy digestion, in fact so that the stomach can easily assimilate them. This water is the bone of contention between public analysts and milkmen, and nothing mas more common three or four years ago than to hear a long cross-examination directed solely to the elucidation of the very knotty point-as to whether there was any difference between the water natural to milk, which in fact the cow put into it, and the water vhich the milkman added. I should like to consider next, by the aid of a set of samples which have been lent me by the Aylesbury Dairy Company, the mode in which the milk is divided by the dairymen into the different articles of commerce which are most frequently made from it.The samples to some extent speak for themselves, and certainly as regards the first series, that of old milk, I need not detain you any longer except to say that here we have fat, caseine, and sugar, dl shown in the same form as in the larger bottles on the table. Our next two series of samples here show us the division of the whole milk into cream and skim milk. Cream, as I took occasion to tell you some time ago, does not consist entirely of butter fat, but contains fifty to sixty-five per cent, more or less aocording to its quality.And in this series of samples we have the cream divided into the constituents present in a good ordinary commercial sample, and you will see that some thirty per cent. of water is still present, and that this water carries withit caseine, albumen, and salts. We may in fact put it another way, and say that separate any particular constituent of tho niilk as carefully as possible by mechanioal means, and we always find that some small proportion of the other sonstituents are present, thus, referring to skim milk : in the first separation we ficd that it still con- tains some fat ; the amount in skim milk is extremely variable, according to the mode of manufacture. The Centrifugal machine, which you can see at work in the south gallery, is by far the moat efficient and most successful for separating the cream from the inilk. The principle of the centrifugal sepallator is practically identical with the principle of skimming, although the two processes appear so dissimilar, The milk revolving iu theTHE ANALYST.179 - separator at great speed acquires immensely increased centrifugal force, which corres- ponds to the force of gravity. This centrifugal force acts more stronglyon the heavy non-fatty portion of the milk and less strongly on the cream, and consequently the non- fatty part of the skim milk gravitates by the centrifugal force to the outside of the revolving circle, leaving the cream to flow away in the inside in an almost pure condition. A few weeks ago I tried experiments with each of the separators at work in these dairies, and in some cases found the proportion of fat present in the skim milk reduced to even less than -1 per cent.These separators at the time produced cream of high quality, and the skim that they produced is more palatable, than skim milk obtained by the old process. I have known this statement to raise a smile on the faces of those who thought they knew all about milk and Lave wondered how it waa possible that one skim milk could be more palatable than another, but the reason is not far to seek; mechanical action in the separator thoroughly aerates the skim mill while it is fresh and has lost none of the aroma peculiar to new milk. Milk exposed to the action of air for twelve or eighteen hours in open vessels loses its aroma, and is apt to become contaminated by an impure atmosphere.Here we have the other constituents of skim milk separated, by which you wiil see that we have a very smaltll increase in the proportions of sugar, caseine, and salts, due t o the proportion of fat that has been removed. Our next array of samples show us a further sub-division. Here we have the cream divided into its two constituents of butter and butter milk. Still the same rule holds good of the constituente of tho original milk passing through, though in diminished proportions, into the finished product. Thus butter always contains milk, sugar, and caseine or curd, and even soluble albumen is not entirely washed away with the butter milk. Still the butter milk, as we see by the central bottle, retains fat-t ue butter fat, which of course represents so much waste in the process of butter making.Taking the other side of our cam, where the skim milk heads the columns, we have skim milk divided up into cheese and whey. The cheese is represented here by the proportions shown. One of these types is skim milk cheese with its very small proportion of fat. These cheeses are common enough, and are usually consumed in this country, but there are many cases in which the use of whole milk cheese, containing a large proportion of fat, is desirable rather than cheeses containing SO little fat. The proportion of fat contained in these cheeses vary, from skim milk cheeses occasionally to be met with containing aa little as three per cent. of fat, up to cream cheeses in which the proportion of fat is largely in excess of the proportion of caseine.Now every one of thsse CoIistituents we dorive from pure milk is capable of being adulterated. There are one or two of these adulterations to which it is necessary I ahould refer. The most serious portion of adulteration unquestionably is the admix- ture of butter with foreign fats, and the substitution of inferior fats for the true butler prssent in chew.180 TEE ANALYST. ~~ ~ We will take the latter first. Alarge number of cheese consumers desire a cheese containing a considerable proportion of fatty matter. This fatty matter, of course, ought to be the butter natural to milk, but butter is far more valuable than oleomargarine, and therefore extensive manufactories have been established for the production of oleomaxgarhe cheese. This cheese is made of skim milk, skimmed by separators, so that the butter is practically all abstracted, the deficiency of fat being replaced by the addition of oleomargarine or lard, in sufficient quantity to make the cheese a tolerably fat one.I look upon this as an exceedingly flagrant adulteration ; the more so because it is one which is hardly likely to be detected by the consumer. There is no difficulty in detecting the fraud by an analytical process. The very worst adulteration in the pro- ducts is of course the use of oleomargarine to mix with, or as a substitute ior, pure butter. I have nothing to say personally against the use of good carefully made oleomargarine as R substitute €or butter, 3 only it is sold under its own name and at a fair price, but I have the greatest objection to its snbstitution for butter, which is more valuable and a more digestible diet, and unqestionably more suitable for domestic use.Good oleomargarine is nothing but the very best of beef fat carefully refined aad carefully churned with milk, and as such no one can dispute its suitability for use as a food ; bad oleomargarine, on the other hand, is a compound of vile refuse fats, clarified and refined in any way that mill chemically fulfil the object in view ; but, to say the least, such a mode of preparing refuse materials for food use is objectionable, and the sale of the inferior sample should be in every way discountenanced. The only reliable and trustworthy method of ascertaining the quality of milk, is by means of a full chemical analysis. To carry this out the water contained in the milk is evaporated.The whole of the solid matters of which I have shown you specimens are left behind in a state in which they can be weighed, the fat contained in these solid matters is then extracted by means of either petroleum or some other suitable liquid, and the solids not fat, which are left behind, are dried again and weighed ; these solids, not fat, form the real standard by which the question of watering is determined, while the fat which has been extracted when weighed forms the leal guide as to whether the milk has been skimmed. If either of these two figures were perfectly constant, one problem of milk analysis would be solved, but unfortunately there is a considerable variation in different samples of milk.To get over this difficulty alow or minimum figure has been adopted a5 the stan- dard, so as to allow an ample margin for the natural irregularity of composition. Milk dealers ara aware of this difficulty in fixing a standard, and are constantly endeavouring to prove that adulterated milk is redly pure milk. There is practically no milk adulter- ation case ever brought into court in which any other defence is raised. The allowance is always said to be insufficient, and the unfortunate milkman has cows worse in quality than those wbich have been tested by the analysts, and, consequently, he obtains milk poorer in quality and worse in character than any which they have seen. This argument, however, has pretty nearly spent itself ; it is only occasionally that there is any magis- trate who is found to listen to it. In conclusion, it d be interesting to notice the extent to which pure milk is sold in London. The returns which are made under the Adulteration Acts specify the per-THE ANALPST. 181 ~~ centage of adulteration found in each sample, while the tabulated reports issued in the blue books state only the number of adulterated samples, and taking the case of milk do not give the percentage of skimming or watering. This, of course, seriously dimin- ishes the value of the returns. It is, therefore, surprising to find that only on one occasion during the last seven years has the percentage of adulterated samples of milk fallen below 20. Out of every 100 samples of milk purchased by the inspectors 20.35 mere adulterated, even on the lenient limit of calculation used. Now this is a very unsatisfactory atate of affairs, and it will surprise no one if f say that I think further legislatiorr is needed to enforce the adoption of a somewhat more rigid standard, and also to increase the efficiency of the supervision at present exorcised over the milk supply. A very much larger number of aamples should be examined, so that purchasers may procure something like a genuine article instead of an adulterated one. I am not at all piwpared to say that this mill not be attended with an increased price in milk ; but that I look upon as a wattor of trifling moment only, if the steps that are taken are such as to ensure an uniform and genuine article.