CONDENSED AND DESICCATED MILKS 651 



1. The Ekenberg System. The milk is clarified by filtering 

 through cotton and passing through a separator after having been 

 warmed in a continuous flow of 90 F. The cream is pasteurized, 

 cooled to a low temperature, and preserved for mixing with sepa- 

 rated milk for the better grades of milk powder. The separated 

 milk is pasteurized, cooled, and stored in an insulated tank from 

 which it is drawn to the exsiccators. The exsiccator is a large 

 vacuum chamber in which a revolving cylinder is hung. Another 

 vacuum chamber the products chamber is separated from the 

 first one by a series of gates. A constant vacuum is thus main- 

 tained when the products chamber is opened. 



A milk chamber, also under vacuum, is attached to the vacuum 

 chamber, and into this chamber the milk is drawn. A specially 

 constructed condenser, to which a suction pipe is attached, is 

 provided with a stream of water, which passes through the con- 

 denser and carries off the vapors. 



A pump forces the milk through a spray pipe on to the revolv- 

 ing cylinder, which is heated slightly by exhaust steam. The milk 

 dries quickly under the influence of heat and vacuum and is removed 

 from the cylinder by silver knives. The temperature of the milk 

 is never above 120 F. and rarely above 110 F. 



The dried milk is completely desiccated by being placed in a 

 chamber of 90 F. for twenty minutes to an hour. The crisp, dry 

 chips and ribbons of milk are then ground to a fine powder. 



2. Atomizing and Hot-air System. Milk is atomized and 

 sprayed into currents of heated air. The dry powder is retained 

 by a screen while the moist air passes through. This process was 

 invented by Robert Stauf, of Posen, Germany, and is successfully 

 used in this country. 



3. The Just System. Two polished metal cylinders are side 

 by side and slightly separated. They revolve inversely at the rate 

 of about 6 revolutions per minute. They are heated by super- 

 heated steam, so that the outer surface of the cylinders reaches 

 considerably above 212 F. The milk flows from a pipe between 

 the rollers and forms a very thin layer on the rollers. The water is 

 quickly evaporated and a knife cuts the milk from the cylinders 

 in continuous sheets, which are caught in receptacles, where they 

 break up. The dry milk is then ground to a fine powder. 



4. The Campbell System. The milk is heated by sterilized air 

 blasts and agitated in a large round copper vessel, and then drawn 

 into rectangular concentrating vessels. These vessels contain coils 

 and are surrounded by hot water. Sterilized air is also introduced 

 into the milk below the surface. This air is under pressure and 

 escapes when the milk enters the tanks, and by this means the 

 water vapor is driven off. As the milk becomes concentrated the 



