i MILK 23 



Certain feeding stuffs impart a characteristic arid often 

 strong flavour to milk, as, for instance, mangels, turnips, &c. 

 Rusty and untinned vessels give a very objectionable metallic 

 taste to the milk. 



The smell of milk should not be at all strong ; a faint animal 

 odour is, however, always to be noticed. Milk very easily 

 acquires the smell and taste of its surroundings ; if, for 

 instance, the stall is badly ventilated, the flavour and smell of 

 dung are soon imparted. These unpleasant properties can also 

 arise from the entrance of particles of dung during careless 

 milking. If the cowshed is disinfected with such strong- 

 smelling substances as carbolic acid, lysol, &c., the milk will 

 certainly be tainted with the characteristic odour of these 

 disinfectants. 



A sour smell indicates that the milk is not fresh, and this 

 smell is noticeable before the milk is sour to the taste. It is a 

 sign that the milk sugar is going to be converted into lactic 

 acid under the influence of micro- organisms. 



I. Determination of the Specific Gravity of Milk. 



A determination of the specific gravity of milk must not be 

 made directly after milking, for the specific gravity of freshly 

 drawn milk increases during the five hours following milking. 

 The difference between the specific gravity of fresh milk and 

 that of the same five hours later is about O'OOl. This 

 phenomenon has not yet been satisfactorily explained ; it 

 is possible that the cause lies in the changes that the casein, 

 which is present in a colloidal form, undergoes in the first five 

 hours. 



The instrument generally used for the determination of the 

 specific gravity is the lactometer, one of the most satisfactory 

 types of which is from the design of Soxhlet, constructed by 

 Joh. Greiner of Munich. 1 



This lactometer, sometimes called a milk araometer or milk 

 hydrometer, has a divided scale reading from 1*024 to 1*038, the 

 distance between each division being 7*5 mm. Between the 

 main divisions arc shorter ones corresponding to half a degree, 

 so that it is not difficult with the eye to read to a tenth of 

 1 Neuhauser Strasse, No. 49. 



