27 



type of balance known as the analytical balance (fig. 24), 

 the cream-test balance not being sensitive enough for this 

 purpose. On the other hand, the analytical balance can 

 not be used with advantage in weighing cream charges for 

 the Babcock test. An analytical balance sensitive enough 

 for the purpose can be purchased for from $30 to $40. A 

 set of accurate analytical weights will also be required. 

 Space does not permit directions for using the analytical 



FIG. 23. Double-walled drying oven. 



balance. If the operator is not familiar with its use, he is 

 advised to consult some elementary treatise on quantita- 

 tive chemical analysis. It must be borne in mind that 

 the analytical balance is a very delicate instrument and 

 should be treated accordingly. 



Desiccators. A warm dish can not be accurately weighed 

 on the balance because the heat creates air currents which 

 buoy up the scale pan sufficiently to make the dish appear 



