SUNDRY COXSTITUEXTS. -U 



The author's conclusions difier from those of Soldner, and are : — 



(i.) One-third of the base with which casein is combined in 

 milk is soda and not lime. 



(ii.) Casein forms a molecular compound with calcium phos- 

 phate. 



(iii.) The citrates are dibasic, and not tribasic. 



Other Constituents of Milk.— Besides the constituents men- 

 tioned, minute traces of silica, iodine, fluorine, acetates, and 

 thio-cyanates have been described. 



None of the salts of milk require a detailed description. They, 

 toi^other with the acids and bases foinposing them, are described 

 in any elementary book on chemistry. 



Among the other substances present in traces in milk the 

 following have been described : — Urea, hypoxanthine and other 

 nitrogenous basic substances, a colouring-matter, odorous sub- 

 stances and alcohol (desciibed liy Brilianip, but certaiiilv nut 

 ordinarily present). 



Lecithin, C||H,„|0,,PN, exists in small quantities in milk: 

 on sa|,(initicnti()ii it gives glyceryl phosphoric acid, fatty acids 

 and chdline ; it contains 3-84 per cent, of phosphorus, and ni\es 

 8-8 pi'r cent, of P.jO-, on ()xidati(jn. 



The Gases of Milk. — It is extremely probable that the uases 

 of milk are derived from the air by absorption during and after 

 milkinji. Oxygon, nitrogen (probably argon), and carbon didxide 

 arc present in fresh milk. As the inilk is kept the amount of 

 oxygen decreases and that of the carbon dioxidi' increases ; this 

 is probably due to aerobic micro-organisms, whit'h absorlj the 

 oxygen and give out carbon dioxidi'. 



The gases of milk may also include pioducts of ilecoinposition ; 

 thus in decomposed milk, volatile sulphur compounds of e\-il 

 odour are present. If such, as is probably the case in dirty 

 surroundings, were present during milking they would be absorbed 

 to some extent by the milk. 



The gases have no practical importance. 



ililk is sometimes charged with carbon dioxide under high 

 pressure to form an efiervescing drink. In this case, and in 

 koumiss and kephir, products of fermentation of milk, the carbon 

 <lioxide is an im])intant constituent. 



The Fat of Milk. 



Constitution. — The fat in milk is found in the shape of small 

 j;lobules varving in size, according to Besana, Fleisehmann, and 

 other authorities, from nOl mm. to ()-ii016 mm. in diameter. 

 Then' is some probability that the total weight of globules of any 

 si/.e is ei|ual to the total wei^lit of globules of any other size. 



