178 





H. B. TAYLOR. 





Viscosity 20° C. 



Viscosity 40° C. 

 (observed). 



Viscosity 40' C. 

 (calculated). 



2*032 



1-878 



1*878 



1*953 



1*812 



1*805 



1-997 



1*844 



1*845 



1*966 



1-823 



1*817 



1*961 



1*812 



1-812 



The figures given above represent the viscosities of the 

 milk at 20° C. and 40° O. relative to water at the same 

 temperature. It is well known that when milk is heated 

 to a temperature of about 70° O. a change takes place which 

 is said to render the milk less digestible. If this change 

 takes place in those constituents which have a large influ- 

 ence on the viscosity, it should be possible to detect a 

 change in the viscosity. With this in view experiments 

 were carried out in such a manner that samples of milk 

 were heated to the desired temperature and then cooled 

 to 20° C. again, when the time of flow was measured. When, 

 in successive determinations with increasing temperatures, 

 the temperature to which the milk was heated reached 70° 

 O. the viscosity began to increase, showing that a precipi- 

 tation or coagulation was taking place. By following the 

 above procedure the results given in Table V were obtained. 



Table V. 

 I. II. III. 



Temp, milk 



Time of flow 



Temp, milk 



Time of flow 



Temp, milk 



Time of flow 



heated to 



at 20° C. 



heated to 



at 20° C. 



heated to 



at 20° C. 



25 



162*0 



20 



201*0 



20 



186*0 



45 



158*5 



40 



199*2 



60 



181*8 



50 



160*4 



60 



195-0 



70 



L83-5 



65 



159*4 



80 



203*6 



75 



192-0 



The figures show that tbe change, which is probably a 

 coagulation of the albumen, takes place close to 70° O. 



It was found that the electrical conductivity of a sample 

 of milk did not change by heating to a temperature of 70° O. 



