THE TESTING OF MILK AND CREAM 123 



best difficult to handle and tend strongly toward inaccurate 

 results. 



Weighing the cream into the test bottle 



The cream must be weighed into the test bottle, not meas- 

 ured. This is necessary in order to secure the correct amount 

 by weight. Cream varies in weight with its richness and its 

 mechanical condition, and no one measure will hold the correct 

 amount of cream of varying richness. The correct amount of 

 cream by weight is 9 grams. 

 Cream scales (Plate III). 



The cream scales must be accurate and sensitive to at least 

 tu gram ; they should rest on a firm and level table, be properly 

 adjusted, and kept in good working order. 



Balances of large capacity and holding a large number of 

 bottles are not as sensitive as balances of small capacity and 

 holding a few bottles only. Other factors being the same, the 

 one-bottle scale is the most accurate scale. However, two- 

 bottle, four-bottle, and even twelve-bottle scales, if properly 

 constructed, in good working condition and operated carefully, 

 answer all practical purposes; they are sufficiently sensitive 

 for this work, and their relatively large capacity simplifies the 

 cream testing problem and avoids unnecessary expense. 



The balances should be kept dry and protected from corro- 

 sive influences such as sulfuric acid, salt, etc. During operation 

 the scales should not be exposed to drafts, and the weighings 

 must be made accurately. After the bottles are placed on the 

 scales, the scales should be properly balanced before any cream 

 is transferred into the bottles. If any cream is spilled on the 

 balance, it should be removed before the weighing is completed. 

 Mark each bottle with a number and record this number on 

 the test sheet opposite the name or number of the respective 

 patron. 



