1 86 



Condensed Mii^k and Mh,k Powder 



more expensive 



capacity of the apparatus, but it also involves a 

 equipment. 



In this, as in all other processes, where the desiccation is accom- 

 plished by evaporation on a revolving, steam-heated drum, the rapid- 

 ity and completeness of evaporation are regulated by the tempera- 

 ture and speed of the drum. 



Fig. 57. The Passburg milk drier 

 Courtesy of the Buffalo Foundry & Machine Co. 



4. The Campbell Process. — A current of warm air passes 

 through the milk upward until the milk has become thick. The 

 remainder of the drying is accomplished by exposure to heated air. 

 The dried milk is then ground to a powder. This is the Campbell 

 process, invented in 1900 and patented by J. H. Campbell of New 

 York in 1902, 



