altering its chemical composition to feed certain microbes with, 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, and even if added in the small proportion of twelve grains per quart is said to impart a taste to the milk, and is, moreover, incapable of destroying typhoid bacilli if present.

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.

A Departmental Committee of the Local Government Board was appointed in this country to inquire into the use of preservatives in foods. In their report they state that from 42 up to 126 grains of boracic acid were detected in milk offered for sale, and that on one occasion no less than

80 grains of this material were present in a pint of milk sold to their inspector. It is pointed out that as long as preservatives are permitted there is no guarantee against the addition of excessive amounts to milk, and that evidence has been obtained pointing to an injurious effect of boracised milk upon the health of young children. The Committee report that in Denmark the use of preservatives is strictly prohibited, and the prohibition is strongly enforced; neither are preservatives permitted in Belgium.

The application of heat to milk is, in fact, 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 and the cleanly condition or otherwise of the milk employed.

The difficulties which have to be overcome in producing efficiently sterilised milk are due, in the first place, to the remarkable power of resisting heat which characterises not only some disease germs, but also some of the microbes which are particularly partial to milk; secondly, to the sensitiveness of milk to heat, as exhibited by its alteration in taste and other respects through exposure to high temperatures.

To overcome these difficulties many ingenious pieces of apparatus have been devised, based upon a process originally introduced by Pasteur for pre

venting certain defects in wine and beer, and which consists in the application of a temperature of about 60° Centigrade. This process is known as Pasteurisation, after its renowned initiator.

So-called "Pasteurised" milk has become during the last year or so increasingly popular in this country, whilst on the Continent it has been largely dealt in for several years past, and has commercially proved a great success. Indeed, so strong is the prejudice amongst our neighbours across the Channel against using unboiled milk that in Leipzig and other cities in Germany endeavours have been made by charitable and other societies to encourage the use of sterile milk amongst the poorer classes, whilst it has been stated that the introduction of Pasteurised milk among the poor of New York City, through the philanthropic efforts of Mr. Nathan Straus, has done much to reduce the high rate of mortality amongst infants during the hot summer months. In France, ie. in Paris and Grenoble, in order to reduce if possible the lamentable mortality amongst infants from diarrhoea in the summer months, which was largely attributed to the use of unboiled milk, sterilised milk was distributed to the poor at the cost of the community in general. In Grenoble, according to statistics collected by Berlioz during the years 1894-6, the death-rate of infants under a year old

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in the months of July, August, and September fed on raw milk reached 69.3 per 1,000, whilst amongst those supplied with sterilised milk it was reduced to 27.9 per 1,000.

Just, however, as all is not gold that glitters, so all sterilised milk so-called is not necessarily free from bacteria. Indeed, according to a recent German authority, "the complete and certain sterilisation of milk is not yet to hand."

Dr. Weber examined the sterilised milk as supplied by various companies in the city of Berlin. As many as 150 bottles were tested from eight different sources, with the result that not one of these eight companies was found to be supplying milk free from bacteria, or, in other words, what it professed to be-sterile. True, the percentage of sterile bottles varied from 5 per cent. in some of the supplies to 86 per cent. in others.

Thus it may be realised how, as has been already pointed out, difficult a matter it is to devise an efficient apparatus for the reliable sterilisation of milk. So far it appears that the best results have been obtained with an apparatus devised by Flaack, a director of the Brunswick Sterilising Milk Company, and known as the Flaack apparatus. Exhaustive examinations made during the course of a whole year in the Hygienic Institute at

Würzburg never once showed a failure, all the samples tested being germ-free.

Some supervision is, therefore, necessary in the case of these milk-sterilising companies to ensure that the public is obtaining what it is paying for, as it has been shown by Professor Flügge, a worldrenowned authority on the subject of milk and its sterilisation, that the bacteria left over in these so-called sterilised milk samples are by no means invariably a harmless residue, but, on the contrary, may consist of individuals which he has gathered together in a class under the heading of poisonous peptonising bacteria, and which owe this unfortunate designation to the rapidity and energy with which they can engender the putrefaction of albumen. As indicating how essential it is that every detail in the sterilisation of milk should be adequately assessed, I may mention a paper recently published by H. L. Russell and E. G. Hastings, of the Wisconsin Agricultural Experiment Station in the United States, on the importance of Pasteurising milk in closed rather than in open vessels, bacteria having been found more resistant in milk when heated in contact with the air than in closed vessels, this variation being attributed to the formation of a surface pellicle, which readily forms on milk when heated in open vessels to a temperature of about 60° Centigrade