Scientific Intelligence. — Chemistry. 379 



Much of the milk sold by certain milk men at the corners of 

 streets, has none of the properties common with milk, except the 

 whiteness. 



The quantity of the milk which proceeds from the same COW, is 

 very different at different times ; and that of different cows varies al- 

 so in quality. 



Some of the more wealthy inhabitants who obtain their milk di- 

 rectly from the dairies, at a good price, have it pure ; — but the mass 

 of milk sold in Paris is always more or less altered. 



The most common adulteration is that of water. But as this can 

 be detected by the taste and color, brown sugar is added to restore 

 the sweetness, and wheat or some other kind of flour, the whiteness 

 and consistency. 



Hence the areometre which merely determines the specific grav- 

 ity of the fluid, is of no use in detecting these impurities ; — and be- 

 sides, milk which is rich in butyraceous matters is much lighter than 

 that which is less rich in butter, but more rich in caseous ingredients. 



To prevent the flour which is used in thickening the skimmed and 

 watered milk, from settling to the bottom, it is previously mixed with 

 water and boiled, which renders it when cold, soluble in the milk. 



Thus flour is easily detected by the tincture of iodine, which gives 

 it a wine or violet color. 



More especially, if this floured milk be heated with a little sulphuric 

 acid, the coagulum separated by a filter, the serum acquires a fine 

 blue color by the tincture of iodine. 



Thus detected, the milk sellers sought for some substance which 

 would not produce the blue color with iodine, in which they doubtless 

 obtained the aid of some chemists. They resorted to an emulsion of 

 sweet almonds, with which, for the cost of about one franc, they can 

 give a milk white to thirty pints of water, and communicate no un- 

 pleasant taste. 



Some of these pretended milk dealers, less scrupulous, employ 

 hemp-seed in lieu of almonds, because of its greater cheapness. They 

 thus dilute the milk of cows to almost any extent they please, with- 

 out altering its color or opacity, and correct its taste by a little coarse 

 sugar. 



This factitious milk may be detected, however, by the oily nature of 

 its curd. When the latter is pressed between the fingers, or on pa- 

 per, the oil exudes from it, which is not the case with the curd af 

 pure milk. 



