21 



Weighing the charge. After the sample has become homo- 

 geneous throughout, the charge is quickly weighed into 

 the test bottle . The weight of the charge depends upon the 



FIG. 17. -Type of knife-edge cream balance. 



style of bottle used. For this purpose the 9-gram bottle 

 is recommended. A pipette is useful in conveying the 

 cream to the test bottle, as the flow can be easily controlled 



FIG. 18. Type of torsion balance for single bottle, 



and checked on the drop when the pointer of the balance 

 indicates that the correct quantity has been run in. This 

 weight must be exact, and some experience is necessary 

 before the charges can be quickly and accurately weighed. 



