MILK POWDER 267 



The machine consists of a cylindrical device inside of 

 which rotates slowly a nickel-plated drum. The interior 

 of the drum is steam-heated. An air pump creates a 

 vacuum. The milk is put into the bottom. The ro- 

 tating drum picks up a film of the milk and dries it prac- 

 tically instantaneously, although the temperature is only 

 about 104 F. 



Scrapers take off the dried milk from the drum and 

 discharge it into a receiver on the side, through valves 

 which open and close intermittently. 



The Modern Method. A description of the latest 

 and, so far as known, the most successful method of milk 

 desiccation is given by L. C. Merrell in a paper read 

 before the Syracuse Section of the American Chemical 

 Society, 1908. 



" Fresh whole milk is drawn into a vacuum pan and a 

 portion of its water removed. This condensation is halted 

 while the milk is still in a fluid condition and before any 

 of the milk albumen has been cooked on to the walls of 

 the vacuum chamber. The milk is then drawn from the 

 vacuum pan and sprayed into a current of hot air. The 

 moisture of the milk is instantly absorbed by the air and 

 the particles of milk solids fall like snow. Upon exami- 

 nation, they are found to contain less than two per cent of 

 moisture. The hotter the air is, the more rapid the dry- 

 ing effect and the less danger there is of injuring the milk 

 solids by heat. 



" This method of desiccation does not destroy the globu- 

 lar condition of the butter fat, it does not burn the milk 

 sugar, nor does it coagulate the albumen of the milk. It 

 is not necessary to neutralize the acidity of the milk, for 

 the moisture is removed so quickly that there is no chance 

 for chemical action, and neither the casein nor the albumen 

 is effected in any way by the concentration of the acid. 

 The difficult pasty condition of the milk solids is passed 

 while the milk particle is suspended in the air and not in 



