THE BUTTER OVERRUN 1 79 



chemical changes and be reduced in strength. Such changes 

 take place very readily if exposed to light. It is therefore 

 necessary for the operator to prepare his own solutions, which 

 should be prepared in rather small quantities. Chemically pure 

 silver nitrate, AgN03, should be used. This may for the sake 

 of convenience be weighed into small gelatin capsules, each 

 capsule containing 2.906 grams. If chemical balances are not 

 available a druggist might be able to do such weighing; if not, 

 the capsules of silver nitrate might be supplied by a manu- 

 facturing chemist. The capsule is closed and wrapped with tin- 

 foil to exclude the light. Such capsules have been kept in a 

 dark, dry place for several months in perfect condition, although 

 it is recommended that the silver nitrate be put up in small 

 brown bottles if to be kept to exceed two months. 



Preparing the Silver Nitrate Solution. — A gelatin capsule is 

 placed in the flask and from 200 to 300 c. c. of distilled water 

 heated to within a few degrees of boiling are added. The flask 

 is shaken with a gentle rotary motion until the capsule with its 

 contents has been dissolved. The flask is then wrapped with 

 brown paper in order to exclude the light and it is left in a dark 

 place until the temperature of its contents is the same as that 

 of the room. The flask is then filled to the 500 c. c. mark with 

 distilled water (condensed steam) of room temperature. The 

 solution is kept in a place where light is excluded. 



B. The Potassium Chromate Solution. — Ten grams of 

 potassium chromate are dissolved in 90 c. c. of distilled water. 



C. Manipulation of the Test. — A representative sample 

 from the butter to be tested is secured. The beaker containing 

 the butter is placed in warm water until the butter which is 

 being constantly stirred is of the consistency of a sirup, when it 

 is transferred to ice water and stirred with a spatula imtil the 

 butter congeals. Ten grams of this sample are weighed into a 

 beaker. To this is added about 25 c. c. of hot distilled water. 

 After the butter has been thoroughly dissolved the contents 

 of the beaker are transferred to the 250 c. c. graduate. The 

 beaker is rinsed several times with distilled water which is 

 transferred to the graduate, using about 25 c. c. of water at a 



