THE SPRAY PROCESS 307 



and that the total solubility is very slightly greater in the case 

 of the more flaky milk powder made from uncondensed milk. 

 In these experiments the amount of milk powder, the amount 

 and temperature of the water and the kind and amount of me- 

 chanical agitation were exactly alike. At the end of one minute 

 from the time the milk powders were put into the water, the 

 amount of solids dissolved was practically the same in the case 

 of the flaky powder made from uncondensed milk as it was in 

 the case of the granular powder made from pre-condensed milk. 

 And after that the percentage of total solids dissolved from the 

 powder made from uncondensed milk was slightly greater than 

 the percentage of total solids dissolved at the end of the same 

 respective periods of time from the powder made from pre-con- 

 densed milk. 



Here again it should be understood that uncondensed milk 

 may be so atomized and dried (large orifice of spray nozzle and 

 low pressure) to increase the size and granular condition of 

 the particles of the resulting powder sufficiently, so that for 

 all purposes for which milk powders are used commercially and 

 domestically the ease or difficulty of solution is no longer any 

 factor. 



Effect of Pre-condensing on Recovery of Spray Milk Powder. 

 The finer, lighter and more fluffy the milk powder the greater 

 is the tendency of a portion of the powder to escape from the 

 drying chamber. Hence it is obvious that the product from un- 

 condensed milk, when desiccated in such a manner as to intensify 

 the flakiness at the expense of a granular condition (small orifice 

 of spray nozzle and high pressure), will tend to escape from 

 the drying chamber more profusely than the more granular 

 powder made from pre-condensed milk. Pre-condensing facil- 

 itates maximum recovery. 



It should be borne in mind, however, that the fineness of 

 some of the particles of dried milk made from either uncon- 

 densed or pre-condensed milk, makes necessary the use of an 

 efficient dust collector. Without such a dust collector, a portion 

 of the finer and lighter particles will be lost in either case. In 

 the case of the flakier and finer product of uncondensed milk, 

 the dust collector must be such as to collect a product of that 



