22 MILK HYGIENE 



by chymosin as a firm, jelh'-like mass. The butter-fat 

 contains a yellow coloring- stuff. 



The qualitative composition of cow's milk averages 

 as follows (Fleischmann) : water, 87.75 per cent.; fat, 

 3.-1- per cent. ; casein, 3.0 per cent. ; albumen, 0.5 per 

 cent. ; lactose, 4.6 per cent. ; salt, 0.75 per cent." Lacto- 

 globulin and lecithin are found only in very slight quan- 

 tity; citric acid is found in quantities of from 0.1 to 

 0.15 per cent. Analysis of the ash shows its constitu- 

 ents to be present in the following proportions : 



KjO Na^O CaO MgO Fe^ O,, P., O3 CI SO, 

 25.81 11.78 19.71 2.77 0.13 23.11 16.15 4.07^ 



But there may be a considerable amount of variation, 

 especially in the potash, magnesia, chlorine and sul- 

 phuric acid, since the consumption of certain salts in 

 great quantity cause changes in the composition of the 

 ash. The quantitative composition of cow 's milk varies 

 greatly among the different breeds and individuals, and 

 at different stages of the period of lactation (see the 

 next section). 



Zebu's Milk coincides almost wholly in its properties 



" Richmond gives tlie following average composition of milk, 

 based on the analysis of 200,000 samples taken from the supply of a 

 dairy company in London : 



Percent. Per cent. 



Water 87.10 Casein 3.00 



Fat 3.90 Albumin 0.40 



Milk sugar 4.75 Ash 0.75 



A very large proportion of the cows producing milk for the 

 London market are of the Shorthorn breed. [L. P.] 



The following is taken to represent " milk of good average 

 quality " in Massachusetts : 



Per cent. Per cent. 



Water 87.00 Casein 3.00 



Fat 4.00 Albumin 0.50 



Milk sugar 4.80 Ash 0.70 



(Bulletin 110, Hatch Experiment Station.) [L. P.] 



