so characteristic of the tubercle bacillus, for Currier has shown that to effectually destroy this micro-organism in water a temperature raised to the boiling point maintained during ten minutes is necessary. The power to withstand exposure to high temperatures is possessed in very different degrees by different microbes; thus the cholera bacillus cannot survive even a momentary exposure to a temperature many degrees below boiling, whilst typhoid and diphtheria bacilli are destroyed when the water reaches the boiling point.

There are, of course, various methods of obtaining germ-free milk; -some are, however, attended with too great labour and inconvenience to admit of their practical application. Thus some time ago, wishing to prepare some sterile milk for bacterial cultivation purposes without altering its chemical composition, I had to patiently heat it for from one to two hours on five successive days, watching the while that the temperature remained between 58 and 65° Centigrade! The milk was sterile and I kept it for months, but such a process of course is impossible for domestic purposes.

The addition of chemicals to milk is both undesirable and ineffectual; amongst such substances boracic acid, borax, and salicylic acid are employed; but whilst the two former have been found to produce but little effect upon disease germs present in milk, salicylic acid hinders curdling more than other substances, but even if added in the small proportion of twelve grains per quart gives a taste to the milk and is not capable of destroying typhoid bacilli.

Authorities are, moreover, not agreed as to the harmlessness of this ingredient, and in France the employment of salicylic acid in the preservation of food is strenuously opposed by doctors who consider its habitual use injurious to health. The application of heat to milk is the only advisable and reliable method for rendering it free from germs, but a great deal depends upon the manner in which the heat is applied.

It is unnecessary here to detail the numerous efforts which have resulted in the elaboration of various descriptions of so-called 'milksterilisers,' the efficiency of which have all undergone searching investigations at the hands of bacteriologists as regards their destruction of disease germs.

The difficulties which have to be mastered consist, firstly, in the remarkable power of resisting heat which characterises not only some disease germs, but also some of the microbes which are most partial to milk; secondly, in the sensitiveness of milk to heat as exhibited by its alteration in taste and other respects through exposure to high temperatures.

To overcome these obstacles many ingenious pieces of apparatus have been devised, based upon a process originally introduced by Pasteur for preventing certain defects in wine and beer, and which consists in the application of a temperature of about 140° Fahr.

The process is usually described as the 'pasteurisation' of milk, and very perfect apparatus has now been provided in which milk is maintained at a temperature of from 154-156° Fahr., generally through the agency of steam. of steam. A special contrivance is also provided by means of which during the process the milk is kept in continual movement, so that it does not acquire a burnt flavour; the temperature is also prevented from rising to 158° Fahr., at which point the change in taste, which it is desirable to avoid, commences. By observing these precautions much of the popular objection raised to boiled milk is removed. It is extremely satisfactory to learn, on the authority of so careful an experimenter as Dr. Bitter, that pasteurisation in the most approved apparatus for from twenty to thirty minutes kills with certainty all the disease germs such as those of tuberculosis, cholera, diphtheria, and typhoid which are likely to be found in milk.

It must not be supposed that the pasteurisation of milk necessarily relieves the dairyman of all responsibility as regards the conditions of his dairy, that he may with impunity neglect precautions of cleanliness, &c. ; on the contrary, more and more attention is being directed to the importance of cleanly milking and the obser vance of other hygienic considerations in dairy work, for experience has shown that it is far easier to sterilise clean milk than milk contaminated with thousands of bacteria obtained through neglect of, and inattention to, simple sanitary requirements. Some idea of how imperative such precautions are may be gathered from investigations recently made on the milk supply of Berlin, for Dr. Backhaus has estimated that this city alone consumes daily with its milk 300 cwt. of cow-dung!

Pasteurised milk may be prepared in bottles, and special devices have been introduced so that the latter are closed whilst still heated and under pressure, thus avoiding any chance of bacterial infection taking place at the moment of closing the bottles.

There is no reason why cream should not also be pasteurised before being sent out from the dairy, not only for direct consumption but for the production of butter. Pasteurised cream lends itself very readily for this purpose, for although the actual yield of butter is said to be rather less, it is stated to be of a superior quality.

Another application of pasteurised milk is in the manufacture of cheese. Such milk curdles very readily with rennet, and investigations are now in progress for the production of particular varieties of cheese from pasteurised milk by means of particular microbes; for although many varieties of bacteria are not only not wanted in, but are detrimental to the quality of, as well as safety of, dairy produce, there are many germs which play a most useful and indeed absolutely indispensable part in the dairy. Our exact information on this branch of the subject is at present very limited, but researches are being vigorously pursued, and some already of the use

ful and friendly dairy bacteria have been distinguished; for example, a bacillus has been found which is responsible for the production of that variety of Swiss cheese known as 'thousand-holed' on account of its porous or cavernous structure. This appearance is due to the production of bubbles of gas by a bacillus which causes the curd to 'heave,' thus leading to the formation of large holes.

There is a wide field for research open for workers in this direction, and it is one which will doubtless occupy the attention of the authorities in some of our recently created agricultural colleges. There can be no doubt that, before long, a well-appointed dairy will have its supply of particular bacteria much as a chemical laboratory is furnished with suitable reagents, and instead of depending upon chance for the production of particular cheeses, any desired variety of the latter will be produced at will by means of special microbes with almost the same certainty as a chemist can obtain a particular chemical reaction.

It is earnestly to be hoped that before long the public will themselves insist upon the distribution of untainted milk; at present, the request for sterilised milk at any of our dairies would be met with blank ignorance on the part of the employé as to what was meant by the inquiry. On the Continent a very different state of things exists, and so strong is the prejudice against drinking unboiled milk, that in Leipzig and other cities in Germany serious endeavours have been made by charitable and other societies to encourage the use of sterile milk amongst the poorer classes. It has also been recently claimed that the introduction of pasteurised milk among the poor people of New York city, through the philanthropic efforts of Mr. Nathan Straus, has done much to reduce the infant mortality during the hot summer months.

The Swiss, alive to the pecuniary importance to be derived from the supply of such milk, have established milk sterilising associations, and in Paris important companies exist for the production and regular delivery of 'lait pur stérilisé.' There is surely room in this country, were but the facts sufficiently well known and the dangers realised of using raw milk, for the successful establishment of such associations, not alone on hygienic grounds, but from a purely commercial point of view.

Who would not thankfully exchange, for example, the tumbler of dust-laden, germ-swarming milk which is handed round at our railway stations, or provided in our crowded non-alcoholic luncheon saloons, for a flask of milk guaranteed to be sweet and free from all contamination?

If only in the extension of its keeping power, surely pasteurised milk has a future which must commend itself sooner or later to agricultural authorities here as it has already done on the Continent.

It is satisfactory to learn that some of the objections which have

been raised to the use of boiled milk, on the grounds of its unwholesomeness are not regarded, by those best qualified to form an opinion, as proven. Some years ago, after the National Health Society had circulated a leaflet which I wrote for them on the advisability of boiling all milk before use, I was invariably confronted with arguments as to its unfitness for children on account of its indigestible character. My personal experience is, however, quite contrary, and although the use of raw milk has been for years most rigorously prohibited, none of the evil results foretold have resulted.

This question has, however, been thoroughly investigated by the present Director of the Institut Pasteur, Dr. Duclaux, who published a short time ago an exhaustive article on 'La digestibilité du lait stérilisé,' in which he carefully examines and weighs all the facts which have arisen, and reviews the numerous special researches which have been made in connection with this subject.

I cannot do better than quote some of the words with which he concludes his article: Ceci nous amène,' he writes, 'à une conclusion qu'il faut bien avoir le courage de tirer, c'est que ces études chimiques sur la digestibilité du lait ne sont pas adéquates à la question à résoudre. . . . En attendant, tenons-nous-en à cette conclusion générale, que le lait pasteurisé, chauffé ou stérilisé, est encore du lait, devant la science comme devant la pratique, et que si son emploi présente parfois des inconvénients, ceux-ci sont légers et amplement compensés par les avantages.'

G. C. FRANKLAND.

1896

A NORTHERN PILGRIMAGE

LONDON was hot-very hot. The season was growing stale. 'No more dining out,' said the wise physician; 'try a few days in a bracing atmosphere.' A bracing atmosphere! I drew in a long breath of the tepid air. I might have been inside an oven. Where, at such a time as this, was there anything that could truly be called bracing to be found short of the Arctic Circle? And then in a blessed moment of inspiration there suddenly flashed upon me the vision of my native county-practically unseen for two-and-thirty years. As in a dream I saw the league-long roller breaking in silver on the iron coast, and heard the plovers calling on the rolling moorlands that look down on Coquet and Aln, and felt the city of my youth quivering beneath the blows of her clamorous iron flail.' Unseen for two-and-thirty years, and the generation I had known gone from it for ever, all the dear remembered faces of my childhood vanished with it! It was the memory of that generation that stood between me and the place I longed to see again. How could a man go back to the old home that was home no longer? But out of the far-off past came a sudden call before which my hesitation vanished—a call that found an echo in my heart; and thus it came about that, four-and-twenty hours later, I found myself seeking repose in the Station Hotel at Newcastle-on-Tyne.

6

One station hotel resembles another as closely as twin peas in the pod. When I breakfasted next morning in the coffee-room there was nothing in my surroundings to remind me of the town once so familiar. That which struck me was the distinctly cosmopolitan air of the company at breakfast. At one table they were talking Russian, at another Spanish, whilst at a third, a demure Japanese with almond-shaped eyes was studying the menu. It was not thus in the early sixties; but since then the world has discovered Newcastle, and has learned what the men of the Tyneside can do for it. By-and-by some neighbouring chairs were filled by a party of honest country-folk, and then there fell upon my ears the long-lost music of the Northumbrian tongue-the rolling gutturals, the sing-song cadence, that can be heard nowhere else in this world. I knew that I was at home at last.