MILK POWDERS. 203 



The milk used to prepare No. 3 is only just above the Govern- 

 ment standard. The normal percentages of lime and phosphoric 

 anhydride in milk are 0'17 per cent, and 0'2.3 per cent, respectively, 

 but vary somewhat with the protein, and the normal acidity 

 is not far from 20°. From a consideration of the results, it 

 would appear that Nos. 2 and 7 have received an addition of 

 saccharate of lime ; and No. 6 has received an addition of a 

 phosphate. Nos. 3 and 4 contain cane sugar, but there is no 

 evidence of the addition of saccharate of lime. No. 1 probably 

 received an addition of sodium carbonate, as the lime is not 

 high enough considering the high protein to indicate an addition 

 of this substance, and No. 5 appears to have received no addition 

 whatever. 



Milk powders containing cane sugar are also made. Two 

 samples examined by the author had the following composition ; — 



Both had a slightly rancid odour and tasto. When dissolved 

 in water some of the fat was not emulsified. 



The Action of Cold on Milk — Composition. — When milk 

 is exposed to a low temperature it partially freezes. Like other 

 aqueous solutions the freezing point is below that of water, and 

 is about — 0"55° C. (31° F.), estimated in the Beckmann apparatus. 

 The frozen portion has not the same composition as the milk 

 from which it was prepared, but contains a larger quantity of 

 water. Owing to the facts that milk has not a point of maximum 

 density, and that it does not freeze as a homogeneous substance, 

 ice never forms in a solid layer on the surface. The following 

 analyses (Table LM.) will show the composition of the ice and 

 liquid portion respectively : — 



