MILK INSPECTION 



201. 



minute so that one can follow it and turn the crank once for each 

 beat. After tubes have rested in the rack 10 minutes the readings 

 may be made. At the lower end the chloroform, then the white mass 

 ■of coagulated casein, and above the clear solution of other solids are 

 seen (Fig. 60). To read: Hold the tube perpendicularly at level 

 of the eyes and note the divisions marking the higher and lower 

 levels of the casein. To find the percentage count the divisions 

 between these levels, or subtract the lower from the higher .level. 



Fig. 60. 



Acetic acid. 



Casein. 



Chloroform. 



Tubes for Hart's Casein Test. 



If a preservative is used in the milk, only potassium dichromate is 

 suitable — 1 tablet to each 10 ounces of milk, and the sample should 

 not be over 3 or 4 days old. 



The New York Board of Health lactometer has a scale divided 

 into 120 equal parts. 



One hundred on this scale corresponds with a specific gravity 

 of 1.029, which is falsely supposed to represent the minimum 

 specific gravity of pure milk; while o on the scale equals 1,000, or 

 the specific gravity of water. The whole scale is founded on the 



