MILK. 435 



Phosphate of lime, 



Phosphate of magnesia, 



Phosphate of iron, 



Phosphate of soda, 



Chloride of potassium, 



Soda, combined with lactic acid, 



3-697* 



Lassaigne observed that milk from the cow forty-two days 

 thirty-two days, and twenty-one days before parturition contain- 

 ed no sugar of milk and no lactic acid, but a sensible quantity of 

 uncombined soda. In short, it bore a close resemblance to the 

 albumen of blood. While milk from the same cow eleven days 

 before parturition and always after it, contained free lactic acid 

 and sugar of milk but no free soda,f It would appear from this 

 and other observations of Lassaigne already noticed, that the 

 milk of the cow is at first very similar to the serum of blood, and 

 that the casein, sugar of milk, and lactic acid, to which it owes 

 much of its distinguishing characters, begins first to make their 

 appearance in it about eleven days before parturition. 



The experiments of Fourcroy and Vauquelin, Thenard, Bou- 

 illon Lagrange, and Berzelius, have added considerably to our 

 knowledge of the constituents of whey. The sugar of milk con- 

 stitutes at an average about 3*5 per cent, of the whey ; while the 

 saline ingredients do not exceed 0*22 or two-ninths of a per cent. 

 The water of course constitutes about 96'3 in the hundred parts. 

 The saline contents of milk are, chloride of potassium, chloride 

 of sodium, phosphate of lime, of magnesia, and a trace of phos- 

 phate of iron, acetate of potash, lactate of potash, lactic acid, and 

 a trace of lactate of iron. 



The colostrum, or beist milk of the cow, has a pretty deep-yel- 

 low colour with a tint of green. It contains a much greater pro- 

 portion of ricottin, and a smaller of casein than milk in its ordi- 

 nary state, and about six days after parturition elapse before the 

 milk contains the normal quantity of these two substances. The 

 colostruih when churned gives a very yellow butter which, when 

 heated, emits a smell similar to that of the white of egg. From 

 the observations of Parmentier and Deyeux, it would appear that 



* Schweigger's Jour. viii. 271. t Ann. de Chim. et de Phys. xlix, 35, 



