MILK POWDER 265 



2. It has good keeping properties. Germs do not multi- 

 ply in skim-milk powder, even at ordinary room temper- 

 ature. 



3. It is a dry substance, making it handy to carry on 

 long sea and land journeys. 



4. A milk of any consistency or richness can be made 

 from it by adding water, making it of special value in 

 baking, candy making, and ice-cream manufacture. 



History and Development of Milk Desiccation. The 

 problem of inventing a proper system of milk desiccation 

 has been worked upon to some extent for more than a 

 century, but more especially during the past sixty years. 



As early as 1810, a man by the name of Appert produced 

 milk tablets, but they did not become of any commercial 

 importance. In 1856 a Mr. Grimwade published a method 

 of manufacturing dried milk. It consisted of sweetening 

 the milk with sugar and at the same time adding carbonate 

 of soda. These substances were added to produce granu- 

 lation in the latter stages of dryness. This mixture was 

 put into a jacketed pan, which was pivoted and kept in 

 constant motion during time of drying. The surrounding 

 jacket was filled with hot water, the temperature of which 

 never went above i29F. When the mixture became 

 pasty, it was poured off into smaller pans, stirred and 

 dried still more; then this paste or dough was passed 

 between marble rollers and pressed into thin sheets. These 

 sheets were then dried with hot air and finally ground to 

 powder. Later the vacuum pan was used in condensing. 



Another process consisted of precipitating the casein 

 and fat by the use of acetic acid or rennet. This curd 

 was drained and then dried on plates at a temperature 

 of between i2oF. and 160 F. The solubility of this 

 powder was restored by adding a little soda. The widely 



