ON BUTTERMAKING 55 



This usually requires about six minutes. Should 

 too much heat be applied at once, the steam may 

 go up above the 15 per cent mark. This should 

 be prevented by withdrawing the heat for a short 

 time. Great care must be exercised in collecting 

 all the moisture in the graduated part if reliable 

 readings or results are to be secured. 



Describe and give directions for using the Mitchell- 

 Walker moisture test. 



The apparatus in this test consists of a metal 

 evaporating cup, condenser, graduated glass re- 

 ceiver, scale for weighing sample, spirit lamp, amyl 

 acetate reagent, and a stand to support the appa- 

 ratus. 



A representative lo-gram sample of butter is 

 placed in the metal cup. To this is added 10 c. c. 

 of the amyl acetate reagent. The apparatus is 

 then connected and the condenser filled with cold 

 water. The alcohol flame is then applied under the 

 evaporating cup. In about a minute the water and 

 reagent will begin to pass over and pass from the 

 condenser tube into the receiver. After all the 

 water has been evaporated from the cup, the re- 

 agent will cease or almost cease dropping for a 

 moment and then begin again as soon as it has 

 reached its own boiling point, which is higher than 

 that of the water. Continue to apply the flame until 

 practically all the reagent is driven off and it ceases 

 to drop freely from the condenser-tube. By this 

 means all the water is washed out of the condenser 

 tube and the major portion of the reagent is recov- 

 ered. The flame is now extinguished. The mouth 

 pf the receiver is corked, and, taken by the top, is 



