64 



Adulteration of Milk. 



Vol. XI. 



Adulteration of Milk. 



The subject of the adulteration of milk, 

 was some time since investigated with great 

 care, by M. Barruel of Paris. Although his 

 observations were intended to apply only to 

 the milk of that city, yet there is little doubt 

 that they will also be found applicable, in a 

 greater or less degree, to all large towns 

 and cities. He commences in stating that 

 all instruments for ascertaining the purity 

 of milk, which are designed to attain this 

 end by indicating differences in its density 

 or specific gravity, are inaccurate and use- 

 less. For on the one hand, pure milk differs 

 much in its density, according to the fodder 

 used by the dairyman for his cows, the buty- 

 raceous matter which imparts lowness of 

 density, being made to preponderate by some 

 kinds of food, and the caseous part, which 

 increases its density, being made preponder- 

 ant by other kinds. And on the other hand, 

 although water, the ordinary substance with 

 which milk is adulterated by the dealers in 

 the French metropolis, would alone cause a 

 great diminution of density, the dealers know 

 ■very well how to prevent that eflect, and 

 thereby render the aerometer or lactometer 

 useless. For this purpose it is only neces- 

 sary to dissolve in the milk a little sugar or 

 sugar-candy, which is required at all evencs, 

 in order to correct the flat taste imparted to 

 milk by diluting it with water. The result 

 of M. Barruel'e inquiries on the adulteration 

 of milk in Paris, was, that no positively 

 noxious substance was, in any case, found 

 in it; that a common practice was to remove 

 a considerable portion of the cream, by al- 

 lowing the milk to stand for a limited time, 

 and then to dilute the remainder, or skim- 

 med milk, with water, and to give it the ap- 

 parent qualities of new milk by one or other 

 of the methods now to be mentioned. The 

 opacity of the milk being much diminished 

 by the water, so that it acquired a bluish ap- 

 pearance, it was at one time usual to correct 

 this defect, by previously mixing wheat flour 

 with the water with which the milk was 

 adulterated. But this deception was too 

 obvious to the senses. Any person, even of 

 indifferent delicacy of palate, could detect 

 the altered taste of the milk; and besides, 

 after two hours' rest, the flour precipitated 

 to the bottom, and the translucent blueness 

 was restored again to the milk. To prevent 

 this inconvenience, the dealers boiled the 

 flour in the water before mixing it with the 

 milk; and in this manner an opaque mixture 

 was obtained, which retained its opacity on 

 standing. As even with this addition, the 

 fabricated liquid had a fiat taste, sugar or 

 sugar-candy was dissolved in it, by which 



means the peculiar sweetness of the milk 

 nearly restored. This adulteration, 



however, had become so easy of detection 

 by means of iodine, which renders a mix- 

 ture of bojled flour and water blue by its 

 action on the fecula of the flour, that M. 

 Barruel was in a belief, that the fraud now 

 described had been but little practised in 

 Paris. Driven from this species of adulter- 

 ation, the dealers resort to another mode, so 

 ingenious, that M. Barruel conceived they i 

 could not have discovered it without the aid | 

 of some scientific person. The method is 

 so simple and cheap, that for one franc — 

 18| cents — the opacity and colour of milk 

 may be imparted to fifleen quarts of water, 

 and so far secret that no disagreeable taste 

 can be detected. This is nothing more than 

 the employment of an emulsion of almonds, 

 for which some dealers, more greedy and 

 less cautious than the rest, substituted hemp 

 seed, which, however, is liable to impart' an 

 acrid taste. By either of these means milk 

 may be diluted to an indefinite extent; and 

 the only corrective required is a little sugar 

 or sugar-candy, to remove the fliat taste. A 

 peculiar advantage possessed by the latter I 

 mode of adulteration over every other, is, 

 that the vegetable animal matter, or vege- i 

 table albumen of the emulsion, by which Si 

 the oil of almonds is held in suspension, is n 

 coagulated or curdled, precisely like casein, j 

 by the addition of acids. This mode of| 

 adulteration, however, may be readily de- I 

 tected by the two following circumstances, 

 viz. — the coagulum or curd, formed by acida 

 in the mixture of milk and almond emulsion, 

 as compared with that formed in milk alone, i 

 is but a little more than one-half; and the* 

 facility with which, by kneading the coagu-cj 

 lum with the fingers, oil may be squeezed^ 

 out of the almond curd, while none exists in^ 

 that of the milk alone. _ i 



Another adulteration to which milk is] 

 subjected in Paris, is to add a small quantityij 

 of sub-carbonate of potash, or of soda, which;* 

 saturating the acetic acid as it forms, pre-j 

 vents the coagulation or separation of curd ;, 

 and some of the dealers practise this with? 

 so much success as to gain the reputation of^ 

 selling milk that never turns. Oflen when; 

 coagulation has taken place, they restore thei 

 fluidity by a greater or less addition of onei 

 or the other of the fixed alkalies. The ace-i 

 tate of potash, or of soda, thus formed, has: 

 no injurious effect on health, and besides,i 

 milk naturally contains a small quantity of 

 acetate of potash, but not an atom of free 

 carbonated alkali. Hence the detection of 

 this mixture is evidently the most difficult 

 of the processes recommended in the various 

 adulterations mentioned in M. Barruel's 



