PHYSICAL PROPERTIES OF MILK 99 



4.3 per cent. About fifteen hours elapsed between the time the 

 milk was drawn from the cows and the time of the tests. After 

 the milk was delivered at the creamery the samples were kept in 

 the refrigerator. 



Though the changes in the specific heat of milk between 15.0° 

 C. and 60.0° C. are not great, still there is shown by our data a 

 fairly pronounced maximum at about 30.0° C. Some of the 

 reasons for this will be discussed later. 

 Specific heat of whey. 



The whey used was from composite milk and was obtained 

 from the cheese vat. There was present from 0.25 to 0.30 per 

 cent fat and the samples were opalescent. The values ob- 

 tained for two samples taken at different times were very near 

 one another. The average specific heat between 23° and 33° C. 

 was 0.975. 

 Specific heat of skim-milk. 



Samples of sweet skim-milk varying in fat-content from 0.30 

 to 0.38 per cent were obtained from a small separator immedi- 

 ately after running through the machine. The average of 

 fifteen determinations on four different samples made between 

 approximately 20° and 40° C. gave an average value of 0.949. 

 Over the pasteurizing range of 60-70° C. the average value 

 of 0.963 was obtained. 

 Specific heats of cream. 



The creams used were sweet and were separated from compos- 

 ite milk in the morning and kept in a refrigerator until evening, 

 when the measurements were carried out. A series of deter- 

 minations was made on each sample over quite a wide range 

 and generally up to about 60° C. 



In the course of the measurements on creams it was found that 

 apparent specific heats considerably above 1.000 were often 

 encountered. This peculiarity of cream was also noted by 

 Fleischmann. The authors' data for 33.5 per cent, 30 per cent, 

 27 per cent, 15 per cent, and 60 per cent creams have been ob- 



