Page:EB1911 - Volume 01.djvu/260

 greater than 60. Milk is the lacteal secretion obtained by the complete milking of one or more healthy cows, properly fed and kept, excluding that obtained within 10 days before and 5 days after calving. Standard milk is milk containing not less than 12% of total solids and not less than 8% of solids not fat, nor less than 3% of milk-fat. Standard skim-milk is skim-milk containing not less than 9% of milk-solids. Standard condensed milk and standard sweetened condensed milk are condensed milk and sweetened condensed milk respectively, containing no less than 28% of milk-solids, of which not less than one-fourth is milk-fat. Standard milk-fat or butter-fat has a Reichert-Meissl number not less than 24 and a specific gravity at 40° C. not less than 0·905. Standard butter is butter containing not less than 82·5% of butter-fat. Standard whole-milk cheese is cheese containing in the water-free substance not less than 50% of butter-fat. Standard sugar contains at least 99·5% of sucrose. Standard chocolate is chocolate containing not more than 3% of ash insoluble in water, 3·5% of crude fibre, and 9% of starch, nor less than 45% of cocoa-fat.”

Numerous other standards with details too technical for reproduction here have also been fixed.

German Empire.—The law of the 14th of May 1879, largely based upon the English Food and Drugs Act 1875, regulates the trade in food. Each town or district appoints a public analyst, and there is a state laboratory in Berlin directly under the control of the ministry of the interior with advisory functions. The ministry, under the advice of this department, issues from time to time regulations concerning the sale of or details specifying the mode of analysis of various products of food or drink. Both in the United States and in Germany, therefore, the executive officers (public analysts) have some authoritative official department for guidance and information.

We now proceed to consider adulteration as practised during recent years in the more important articles of food.

Milk.—Milk adulteration means in modern times either addition of water, abstraction of cream, or both, or addition of chemical preservative. The old stories of the use of chalk or of sheep’s brains are fables. Owing to the wide variation to which milk is naturally subjected in composition, it is exceedingly difficult to establish beyond doubt whether any given sample is in the state in which it came from the cow or has been impoverished. The composition of cow’s milk varies with many conditions. (1) The race of the animal: the large cows of the plains yielding a great quantity of poor milk, the smaller cows from hilly districts less amount of rich milk. Hence, milk from Dutch cows compares very unfavourably with that of Jerseys or short-horns. Watery and acid foods like mangolds and brewers’ grains produce a more aqueous milk than do albuminous and fatty foods like oil-cakes. (2) Sudden change of food, of weather and of temperature. (3) Nervous disturbances to which even a cow is subject, as, for instance, at shows, may greatly influence the composition of the milk. The portion obtained at the beginning of a milking is poorer in fat than that yielded towards the end. Morning milk is as a rule poorer in fat than evening milk. Soon after calving the animal gives a richer product than at later periods, both the quantity and the composition declining towards the end of the lactation. The variations due to these different circumstances may be very great, as is seen from the following analyses, fairly representing the maximum, minimum and mean composition of the milk of single cows:—

In market milk such wide variations are not so liable to occur, as the milk from one animal tends to average that from another, but even in the milk from herds of cows the variations may be considerable. The average composition of genuine milk supplied by one of the largest dairy companies in London, as established by the analysis of 120,000 separate samples recorded by Dr P. Vieth, is fat 4·1%, other milk solids (“solids not fat” or “non-fatty solids”) 8·8%, total dissolved matters (total solids) 12·9%, the variations being from 3·6 to 4·6% in the fat and 8·6 to 9·1% in the solids not fat. It is clear that the 4·6% of fat could be reduced, by skimming, to 3·0%, and the 9·1% of solids not fat to 8·5% by addition of water, without bringing the composition of the milk thus adulterated outside that of genuine milk. In reality even wider limits of variation must be reckoned with, because small farmers sell the milk of single cows, and this, as shown above, may fluctuate enormously. The Board of Agriculture, in pursuance of the powers conferred upon it by the Food Act 1899, issued in 1901 “The Sale of Milk Regulations,” which provide that where a sample of milk (not being milk sold as skimmed or separated or condensed milk) contains less than 3% of milk-fat, or less than 8·5% of non-fatty solids, it shall be presumed, until the contrary is proved, that the milk is not genuine. But even in these cases it is open to the vendor to show, if he can, that the deficiency was due to natural causes or to unavoidable circumstances. The courts have held that when deviations are the result of negligence or ignorance the vendor is nevertheless liable to punishment. Thus, when a vendor omits to stir up the contents of a pan so as to prevent the cream from rising to the top, he may be punished, if by such omission the milk becomes altered in composition so as no longer to comply with the regulations; or, when a farmer allows an undue interval between the milkings whereby the composition of the milk may be affected, he may be liable for the consequences. As the limits embodied in the milk regulations were necessarily fixed at figures lower than those which are usually afforded by genuine milk, and as it is a comparatively simple matter to ascertain the percentage of fatty and non-fatty solids, a strong tendency exists to bring down commercial milk to the low limits of the regulations without coming into collision with the law. The fat of milk is its most valuable and most important constituent. The exact determination of the percentage of fat is therefore the chief problem of the milk-analyst. All analyses made prior to the year 1885 are more or less inexact, because a complete separation of the fat from the other milk constituents had not been obtained. In that year M. A. Adams, by the simple and ingenious expedient of spreading a known volume of the milk to be analysed upon a strip of blotting-paper and extracting the paper, together with the dried milk, by a fat solvent, such as ether or benzene, succeeded in completely removing the fat from the other constituents. Since that time simpler and more rapid means have been based upon centrifugal separation of the fat. When a measured quantity of milk is mixed with strong sulphuric acid, which dissolves the casein and other nitrogenous constituents of the milk, but leaves the fat-globules quite untouched, the latter can easily be separated in a centrifugal, in the form of an oil the volume of which can be ascertained in a suitably constructed and graduated glass vessel, and thus the percentage ascertained very rapidly and accurately; such centrifugal contrivances constructed by H. Leffman, N. Gerber and others are now in general use in dairies, and cheese and butter factories. The amount of “total solids” contained in milk, that is to say, of all constituents other than water, is speedily ascertained by evaporating the water from a measured or weighed portion of milk and drying the residue obtained in a water-oven to constant weight. By subtracting from the percentage of total solids that of the fat the amount of “solids not fat” results, and by cautiously burning off the organic substances, the salts or mineral matters are left. When the percentage of “solids not fat” is less than 8·5 a simple proportion sum suffices to show what percentage of water must be present to reduce the “solids not fat” to the amount found. As the added water also reduces proportionately the percentage of mineral matter natural