340 MILK AND MILK PRODUCTS. XIV. 



Condensed Milk. This is milk which has been concentrated 

 by evaporation in a partial vacuum (so as to perform the opera- 

 tion at a low temperature) and to which sugar, either cane 

 sugar or sometimes glucose, has been added. The extent of the 

 concentration is usually to about one-fourth the original bulk. 

 Sometimes no sugar is employed, but generally about one 

 pound is added to each gallon of milk. 



Whole milk and separated milk are both employed in the 

 manufacture of condensed milk. 



The composition of various forms is usually about 



Sweetened, from whole milk ... 25 11 14 37 10 2 



,, skim-milk ... 29 1 15'5 40 11 2-5 

 Unsweetened, from whole milk 62 11 14 10 2 



They are generally recommended to be mixed with from five 

 to seven volumes of water. The resulting mixture is obviously 

 much poorer in fat and proteids than genuine milk. 



Koumiss is an alcoholic beverage produced from milk by 

 fermentation. As already stated, lactose does not readily 

 undergo alcoholic fermentation. The sugar of mares' milk, 

 however, readily ferments, and an alcoholic liquid can be pre- 

 pared by the addition of a little koumiss, or even sour milk, 

 to mares' milk. Such beverages have been long known in 

 Tartary. 



By the addition of a small quantity of cane sugar and yeast 

 to cows' milk a similar beverage can be prepared. 



The casein at first coagulates, but afterwards partly re- 

 dissolves, and does not appear to be so liable to coagulation 

 under the influence of gastric juice as is that of fresh milk. 

 Koumiss is thus very easily digested and acts both as a stimu- 

 lant and as a food ; it is therefore used for invalids. 



The following analyses of koumiss are given by Wiley : 



Water. Sugar. Alcohol. Fat. Proteid. Acidity. 



From cows' milk 89'32 4-38 0-76 2-08 2-56 0'83 0-47 

 mares' , 91-87 0'79 2-89 1-19 1-91 1-04 



