144 MANUAL OF MILK PRODUCTS 



drops of uniform size. In lieu of a pipette a blunt glass rod or 

 a floating thermometer may be used. Before using, the glass 

 plate should be thoroughly cleaned and dried, as the smallest 

 trace of grease or dirt materially interferes with the accuracy 

 of the results. Ether or alcohol will facilitate the removal of 

 the thin film of grease usually found on glass. The glass should 

 be laid upon a flat table and then by means of the pipette or 

 rod, drops of cream from each sample should be transferred to 

 near one edge of the glass plate. Care should be taken that 

 the drop falls but a little distance so that it will not spread 

 out over too wide a surface. The drops should be placed at 

 least one inch apart. The glass plate should then be inclined 

 at an angle sufficient to cause all of the cream drops to flow 

 slowly down the plate. Creams having the heavier body 

 move more slowly, owing to the greater adhesion of the more 

 viscous fluid to the glass. In order to eliminate any differences 

 arising from slight variations in the surface of the glass or fail- 

 ure to thoroughly remove all dirt, it is better to take a number 

 of drops from each of the creams compared, the aggregate 

 length of the several cream paths then being taken as a measure 

 of the relative consistency, as seen in Fig. 37. 



MILK SEDIMENT TEST (Adapted from Wisconsin Circular 41) 



The amount of sediment found in milk is one indication of 

 its sanitary quality. Dirt in milk is not only unsightly but is 

 also undesirable because of the bacteria which may be carried 

 into the milk with it. Dirty milk usually contains large num- 

 bers of bacteria, some of which may produce very undesirable 

 flavors in the milk or the butter or cheese made from it. It is, 

 therefore, frequently desirable to test milk for the amount of 

 sediment or insoluble dirt which it contains. 



The sediment test is made by straining a pint, or about a 

 pound, of milk through a cotton disk one inch in diameter, 



