MILK AND MILK PRODUCTS 35 



Salt and cane-sugar are occasionally added to milk that has 

 been diluted with water. The former is detected by the taste, 

 the increased proportion of ash and of chlorin. Cane-sugar 

 may be detected, if in considerable quantity, by the taste. 

 Cotton devised the following test: lo c.c. of the sample are 

 mixed with 0.5 gram of powdered ammonium molybdate, and 

 10 c.c. of dilute hydrochloric acid (i to 10) are added. In a 

 second tube 10 c.c. of milk of known purity or 10 c.c. of a 6 per 

 cent, solution of milk-sugar are similarly treated. The tubes 

 are then placed in the water-bath and the temperature gradually 

 raised to about 80°. If sucrose be present, the milk will as- 

 sume an intense blue color, while genuine milk or milk-sugar 

 remains unaltered unless the temperature be raised to the boil- 

 ing-point. According to Cotton, the reaction is well marked 

 in the presence of as little as i gram of sucrose to a liter of the 

 milk, and 6 grams and over per liter are usually found in adul- 

 terated samples. 



The quantitative determination is made by the methods 

 described in connection with condensed milk. 



General Method for Colors in Milk. — Leach has devised a 

 general method for detecting colors in milk. 150 c.c. of the 

 sample are coagulated in a porcelain basin, with the addition 

 of acetic acid and heating, and the curd separated from the 

 whey. The curd will often collect in a mass; but if this does 

 not occur, it must be freed from whey by straining through 

 muslin. The curd is macerated for several hours in a closed 

 flask, with occasional shaking, with ether to extract fat. An- 

 natto will also be removed by it. The ether and curd are 

 separated and treated as follows : 



