Milk ,Suppi,v 



47 



An alcohol lamp ar gas burner on the 

 platform may be used for heating the sample. 

 In this case a few cubic centimeters of the 

 milk are discharged with an ordinary pipette 

 into an ordinary test tube, such as are in com- 

 mon use in the chemical laboratory and can 

 be obtained from the drug store. The tube 

 is held over the flame and the milk comes to 

 a boil in less than a minute. If the milk is 

 in good condition the sides of the glass tube 

 remain perfectly clear. If it curdles upon 

 heating, the sides of the tube show fine specks 

 of the curd. The appearance of these specks 

 condemns the milk. 



The Sediment Test. — This test shows 

 the relative amount of dirt present in milk. 

 One-half pint of milk is passed through a 

 small circle of absorbent cotton and the 



amount of mechanical impurities present in the milk is indicated by 

 the color of the cotton after filtration. In order to hasten the 

 filtration, the milk is forced through the filter under slight pressure, 

 this is accomplished by a rubber bulb attachment to the apparatus, 

 as shown in the accompanying Fig. 7. 



Fig. 7. 

 The sediment tester 



Fig. 8. Cotton Filters 



Clean milk 



Dirty milk 



If the cotton retains a white or creamy color, the milk is rel- 

 atively free from filth. Milk produced under unsanitary conditions 

 stains the cotton brown or black. 



