each taking a pint of the warm milk drawn from an infected cow for four consecutive mornings. On the third day M. Hertwig had feverish symptoms; by the sixth, the mucous membrane of the mouth was swollen; by the seventh, there was a well-marked eruption on the edge of the tongue, the lips, and the internal surface of the cheeks; by the tenth, the vesicles continually increasing in size, had burst; and by the twenty-fourth day the ulcers had dried, and there was some desquamation. MM. Mann and Villain were also affected in the same way, but to a less degree. This experiment is supported by a number of instances of partial epidemics in the human kind, which could be satisfactorily traced to aphthous milk. It would appear certain, that such milk after boiling is harmless. For example, Boulay records that foot-and-mouth disease, when imported into the Commune of Morchier by a pig-dealer, extended in a few days to over a hundred head of cattle, but spared the calves, which were fed on boiled milk and water, and not allowed to suck their mothers.

A New Form of Febrile Disease Associated with Milk.-The milk from a dairy near Aberdeen appears to have been the propagating agent of a peculiar and entirely new malady. This remarkable outbreak has been investigated and described with great ability by Dr. Ewart.* Twenty persons were attacked, and there were three deaths. The symptoms consisted essentially of fever, with one or more relapses, and swelling of the cervical glands, frequently ending in suppuration. The connection of the epidemic with the milk-supply was established by the fact of the illness being confined to those who drank the milk, as well as by the microscopical appearances of the milk, and some well-devised experiments on animals. The microscopic appearances of the milk showed :

1. Numerous micrococci, some free, others in groups or chains. 2. Numerous spores and cells of the yeast-plant. 3. Spores similar to B. anthracis.

Some pus from the neck of one of the patients was found to contain bacilli and spores apparently identical with those found in the milk, and such pus caused fatal illness when injected into small animals subcutaneously. These elements were submitted to cultivation, and a variety of experiments on rats were instituted with the suspected milk, side by side with controlexperiments with healthy milk, the main result being to prove satisfactorily a direct connection between the bacilli and the

* On a New Form of Febrile Disease associated with the Presence of an Organism distributed with Milk from the Oldmill Reformatory School, Aber deen, by J. Cossar Ewart, M.D., Proc. Roy. Soc., 1881, xxxii., 492.

disease; the evidence pointed to a contamination of the water supplying the dairy, and the author concludes that the organism producing this new fever was morphologically not unlike the anthrax organism in its mode of development and life-history; and, further, that it was introduced into the milk after it had left the udder.

DECOMPOSITION OF MILK.

§ 157. It has already been stated that milk left to itself at all temperatures above 9° begins to evolve carbon dioxide, and that this is simply a sign and result of fermentation. If this fermentation is arrested or prevented by any of the means described in the section on the preservation of milk, the fluid remains perfectly sweet and good for an indefinite time.

Besides the production of carbon dioxide during decomposition, a certain portion of milk-sugar is converted into lactic acid, some of the caseine and albumen broken up into simpler constituents, and a small proportion of alcohol produced, which by oxidation appears as acetic acid, while the fat is in part separated into free fatty acids, which ultimately unite with the ammonia produced by the breaking up of the albuminoids. This fermentation of milk is a special kind which of late years has been much studied, and is known as lactic fermentation. Accompanying lactic fermentation, there is nearly always a weak butyric and a weak alcoholic fermentation.

The researches of Pasteur have established the fact that lactic fermentation is produced by a special organism as capable of being sown, cultivated, and, as it were, reaped, as a plant of higher and more complex character. This minute plant consists, like yeast, of a single cell, and propagates like yeast by rapid budding; in mass it is also similar in appearance to yeast, being viscid and of a gray colour. Under the microscope the cells are, however, seen to be very much smaller than those of the yeast-plant, and in common with all very minute particles to be agitated with a rapid "brownian " movement.

A small portion of this ferment, on being added to a solution of sugar, rapidly turns it acid; but the change to lactic acid is never complete, for acidity interferes much with its growth, and brings it ultimately to an end. If, however, the liquid is kept neutral by the addition of chalk, or by any other suitable means, under such conditions most of the sugar is converted into lactic acid. This change is very simple, being merely a splitting

up of one molecule into two more simple equivalent ones, thus-CH12O = 2 C2H2Og

In a few rare instances, butyric fermentation and putrefaction take, in some degree, the place of lactic, and the milk becomes horribly offensive; but this is unusual, and, for the most part, even when the milk is much decomposed, a peculiar, sour, rather faint odour only is noticed. Nevertheless, a weak butyric fermentation is generally present with the lactic; the chief reason why it rarely proceeds to any extent being the fact that an acid medium is very unfavourable to the growth of this particular ferment.

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According to Pasteur, the butyric ferment is essentially an infusorium of the genus Vibrio. The little organisms constituting the ferment have the appearance of minute cylindrical rods, rounded at the extremities, usually straight, either isolated or united in a chain of two, three, or four joints, and even of more. The diameter of these small rods is generally of a millimetre, and the length of the isolated portions from 100 to 180 mm. [0000687 to 000687 inch]. They move forward by sliding. During this movement their bodies remain rigid and undulate slightly; they spin round, they balance themselves on end, and agitate their extremities; they are often bent. The method of reproduction is by fission.* The most favourable conditions for its development are a suitable liquid, slightly alkaline or neutral, kept at a temperature of 40°; the ferment does not require free oxygen.

§ 158. Blue Milk.-Milk has, in rare instances, been known to undergo a peculiar change of colour, becoming of a very marked blue tint, the seat of which is said to be the caseine. On adding caustic alkalies, the colour changes to a cherry red, but the blue is restored by acids. This change is without doubt due to a fungoid growth; the blue principle has never been isolated, but it appears to be volatile.†

ADULTERATION OF MILK.

§ 159. The adulterations of milk in this country, taken in the order of their frequency, are:-The addition of water, the * M. Pasteur, Compt. Rend., 52, p. 344, February, 1861.

On blue milk, the following may be quoted:-Fuchs: Magasin für die Gesammte Thierheilkunde, 7, 133 to 198. Ehrenberg: Monatsberichte der Berliner Akademie des Jahres, 1840, p. 202. Erdmann: Bildung von Anilinfarben aus Proteinkörpern. Journ. für Prak. Chemie, vol. 99, 404, 1868. Haubener: Magasin für die Gesammte Thierheilkunde, Bd. 18, p. 1 to 85, 129 to 204, 370 to 282.

abstraction of cream (or both combined); the addition of cane sugar to conceal watering, the addition of salt, borax, or salicylic acid to milks likely to decompose; and, lastly, the addition of glycerine. Milk is also occasionally manufactured from condensed or concentrated milks. No other adulterations than the above* have been proved to exist by any trustworthy evidence. The mere addition of water is easily detected by the low specific gravity of the milk, which test is really extremely satisfactory, provided the milk is not exceptionally rich in cream, for an exceptionally rich milk may possess a specific gravity similar to that of a watered milk. For instance, a sample of "fear milk," + analysed by the author, was found of a specific gravity of 1019; it contained over 7 per cent. of milk-fat. If, however, the milk is allowed to stand a little while, and the fat then partially removed by skimming, a mistake from specific gravity is not possible. The specific gravity may be taken by the hydrometer, by a Westphall's balance, by a spiral balance (p. 70), or by a specific gravity bottle; in all cases it must be considered as a preliminary test only, its indications should be confirmed or otherwise by subsequent analysis. The amount of water in the milk can only be discovered accurately by analysis and calculation. The analysis is conducted on the principles already explained, and the amount of water calculated from the percentage of "solids not fat." If the exact composition of the

The fable of the adulteration of milk with brains probably originated in a communication made to the Gazette des Hopitaux, Sep. 25, 1841, by an anonymous writer, who affirmed that he had seen in milk, by the aid of the microscope, cerebral tissue and the débris of blood-vessels. This improbable announcement was reiterated by M. Jules Rossignon, who, writing in L'Echo du Monde Savant, gave as an established fact the brain adulteration of milk ("La Cervelle des Chevaux de Montfaucon "). This statement again having been reproduced in Le Memorial Encyclopédique, was afterwards worked up, with additions and amplifications, in various popular periodicals and journals; but, generally speaking, it was not accepted by chemists actually engaged in practical work. In 1844, shortly after the publication of the papers alluded to, MM. Garnier and Harel declared in their work ("Des Falsifications des Substances Alimentaires "), "We have never met in commerce a single sample of milk falsified with brain; we have examined milk bought in different quarters of Paris, and especially among the poor, but we have never found an atom of cerebral matter. With regard to cream also, they justly say, that brains are not suitable for the production of cream, communicating to it a disagreeable taste, and not thickening it. Gautier de Chaubry also undertook some elaborate experiments, showing how extremely difficult it was to mix brain-matter with milk, and when it was effected, how different the milk was from ordinary milk.

A small can of exceptionally rich milk has been occasionally carried by milkmen for the purpose of serving any inspector. Such milk has been termed "fear milk."

original milk is known, then the amount of water added may be with accuracy calculated from the following formula:—

in which y denotes the original amount of "solids not fat," & the amount of "solids not fat" in the watered sample, and x the number of parts of genuine milk in 100. As this useful knowledge is in practice never obtained, the analyst must use a formula based either on the average percentage of “solids not fat," or on the lowest percentage known to occur. This average thousands of analyses have determined to lie between 9.3 and 9.5 per cent., while the lowest percentage found in healthy fairly-milked animals is about 9 per cent. Calculated on this basis, the formula becomes

This is the standard adopted by the Society of Public Analysts; but as a standard it is too low, and permits the milkman to water the milk at least 2 per cent.; for instance, in the analysis of the milk of 183 cows, milked in the presence of Mr. Carter Bell, and analysed by him, the lowest percentage of "solids not fat" is given as 9.2. Now, to this milk water could be added in the proportion of 2 per cent.; and as six of Mr. Bell's cows averaged "solids not fat" 11.3 per cent., such milk could be watered 25.5 per cent. Lastly, Mr. Wanklyn's average country milk could be watered 4 per cent.; his average town milk 10 per cent.; the milk of the Alderney cow 4 per cent. ; and Mr. Bell's mean of 181 cows (9.9) 9 per cent., to bring it down to the Society's standard.

The author has, therefore, somewhat departed from standards in certifying to the adulteration of milk by water; and in cases where the "solids not fat" exactly reach the Society's standard, invariably analyses the milk carefully, seeking for evidences of watering in the presence of nitrates and sulphates. For cows' milk only contains a trace of sulphuric acid in combination, and is absolutely destitute of nitrates; water, on the other hand, not unfrequently abounds in sulphates, and, if impure, in nitrates. Hence, if a sufficient quantity of the milk can be obtained for the investigation, the finding of nitrates and an excess of sulphates, or both, is fair proof of watering, and an analyst is justified in certifying accordingly, although "the solids not fat" may reach the so-called standard.* In certify.

This is the more necessary since, at the present time, the Government chemists have adopted the untenable standard of 8.5 "solids not fat.

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