1 30 THE CHEMISTRY OF THE TISSUES AND ORGANS. 



By repose and skimming fat, 1; proteid, 3*44; lactose, 5*1; ash, 0*75; 

 water, 89'67. (2) By separator fat, 0*2 ; proteids, 3'4; lactose, 5'01 ; ash, 

 0-75 ; and water, 90'64. 



The presence of citric acid in milk was first shown by Soxhlet. Yaudin l 

 considers that this is not from the food, but produced in the mammary gland. 



The variations in the milk with feeding, species of animal, time of day, 

 etc., are described by Struckmann and Bodeker, 2 Fleischmann, 3 Tatlock, 3 

 Eoihne and Fleischer, 4 and others. 



Salts of cows' milk. Soldner 5 gives the following percentages : 



K0 



CaO ........ 



MgO ....... 



P 2 5 (after correction for pseudo-nuclein) 

 Cl ....... 



0-172 

 0-051 

 0-198 

 0-020 

 0'182 

 0-098 



Of the total phosphoric acid, from 36 to 56 per cent., and of the lime from 

 53 to 72 per cent., is not simply dissolved in the fluid, but is united more or 

 less firmly to the caseinogen. The excess of bases over mineral acids is united 

 to organic acids, such as citric. Bunge found 0-00035 per cent, of iron. 



The gases of cows' milk have been analysed by Setchenow 6 and Pfiiiger. 7 

 There are small quantities of oxygen and nitrogen, and from 5 to 10 per 

 cent, of carbonic anhydride. 



In comparing the composition of cows' milk with that of human milk, 

 the main difference consists in the high percentage of proteids, fats, and 

 salts, and the low percentage of sugar in cows' milk as compared with 

 human milk. Qualitative differences will be noted under the headings 

 " Proteids " and " Fats." 



The milk of other animals. Some of the principal analyses are 

 collected into the following table : 



1 Journ. de pharm. et chim., Paris, tome xxx, p. 464. 



2 Ann. d. Chem., Leipzig, Bd. xcvii. S. 150. 3 LOG. cit. 

 4 Landw. Versuchs. Stat., Berlin, Bd. xii. S. 405. 5 Loc. cit. 



6 Ztschr. f. rat. Med,, Bd. x. S. 285. 



7 Arch.f. d. ges. Physiol., Bonn, Bd. ii. S. 166. 



8 Taken from Konig's analyses. The milk is acid, rich in proteids and calcium. The 

 lactose is increased by starchy, and lessened though not abolished by a flesh diet (Benscli, 

 Ann. d. Chem., Leipzig, Bd. Ixi. S. 221 ; Poggiale, Gaz. med. de Paris, Ser. 3, 

 tome x. p. 259). See also Simon, "Die Frauenmilch," Berlin, 1838; Dumas, Compt. 

 rend. Acad. d. sc., Paris, tome xxi. p. 707 ; Kemmerich, Centralbl. f. d. med. IVissenscli., 

 Berlin, 1866, No. 30 ; Szubotin, ibid., No. 22. 



y Taken from Konig. 



10 From Pizzi's analyses (Staz. Sper. Agrar., 1894, Bd. xxvi. S. 615 ; Abstract in Journ. 

 Chem. Soc., London,- 1896, vol. ii. p. 120). Goats' milk differs from cows' milk in smell 

 and taste, and in containing more insoluble volatile fatty acids. In reindeer's milk these 

 acids are less abundant (Solberg, Centralbl. f. agric. Chem., Leipzig, 1896, S. 15). 



11 From Konig. 



12 From Vernois and Becquerel, Union med., Paris, 1867, p. 78. 



