174 H. B. TAYLOR. 



SOME PHYSICO-CHEMICAL MEASUREMENTS ON 



MILK. 



By H. B. Taylor, b.Sc, 



Science Research Scholar, University of Sydney. 



(Communicated by Professor Fawsitt.) 



[Read before the Royal Society of N. 8. Wales, November 5, 1913.'] 



Milk, being the secretion of a living animal, is liable to 

 variations in its composition owing to the influence of internal 

 and external conditions. It is essentially an aqueous 

 solution of milk sugar, proteins and salts, holding in sus- 

 pension fat in the form of finely divided particles. Winter 

 Blyth gives the average composition as follows : — 



Fat ... 3*90 per cent, by weight. 



Caseinogen 3*00 ,, 



Albumen... 0*40 ,, 



Milk Sugar 4*75 



Ash ... 0*75 „ 



Water ... 87*20 



The quality of a milk can be fairly well gauged by the 

 chemical determinations of its constituents, but it was 

 thought desirable to investigate some of the physical 

 properties of milk in the hope that the results might 

 help in the matter of forming an opinion as to its quality. 

 This paper contains an account of experiments on the 

 viscosity, conductivity and reaction to indicators of milk. 



Viscosity. 1 



The measurement of the viscosity was carried out with 

 a capillary viscosimeter, the type used being Ostwald's 

 modification of Poiseuille's apparatus. 



1 The numbers given as the viscosities are the values of * 2 /o 2 /*i/Oi> 

 where t 2 and t 1 are the times of flow of equal volumes of milk and water 

 respectively, and /> 2 andp x the densities. 



