i *o THE CHEMISTR Y OF THE TISSUES AND ORGANS. 
By repose and skimming — fat, 1; proteid, 3-44; lactose, 5*1; ash, - 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. Vaudin * 
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 
Kiihne and Fleischer, 4 and others. 
Salts of cows' milk. — Soldner 5 gives the following percentages: — 
K 2 0-172 
Na o 0-051 
CaO 0-198 
MgO 0-020 
P 9 5 (after correction for pseud o-nuclein) - 182 
CI 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 m ilk have been analysed by Setchenow 6 and Pfliiger. 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 : — 
Reference 
Animal. 
Water. 
Caseinog-en. 
Albumin. 
Fat, 
Lactose. 
Salts. 
to Notes 
below. 
Dog . 
75-4 
9-91 
9-57 
3-19 
0-73 
8 
Cat . 
81-6 
9-08 
3-33 
4-91 
0-58 
8 
Goat . 
86-91 
3-69 
4-09 
4-4.". 
0-86 
9 
Goat . 
86-75 
3-64 
5-35 
3-60 
0-66 
10 
Sheep 
83-5 
5-74 
6-14 
3-96 
0-66 
11 
Sheep 
82-84 
4-7 
4-8 
3-4-6 
0-6 
12 
1 Jourii. depharm. et chim., Paris, tome xxx. p. 464. 
2 Ann. d. Chem., Leipzig, Bd. xcvii. S. 150. 3 Loc. cif. 
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 (Bensch, 
Ann. d. Chem., Leipzig, Bd. Ixi. S. 221 ; Poggiale, Oaz. mid. dc 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. Wissensch., 
Berlin, 1866, No. 30 ; Szubotin. ibid., Xo. 22. 
9 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 Yernois and Becquerel, Union mid., Paris, 1867, p. 78. 
