TESTING BUTTER 633 



One heating arrangement, consisting of an al- 

 cohol or gas burner with tripod and small 

 piece of fine copper wire gauze, or prefer- 

 ably an electric plate, '., . 



One thermometer registering to 300 F. 



Weighing: Have balance properly balanced. See that it 

 swings freely. Keep pans perfectly clean. Check balance several 

 times during the day. Check up weights of aluminum cups weekly 

 by re-weighing, in order to detect loss in weight. Before taring 

 aluminum cups, wash them, dry them, and heat them. Do not use 

 dry scouring powders for aluminum cups. If washing powder is 

 used dissolve it first. Weigh to the third decimal point. Handle 

 weights with forceps only and keep them clean. If they show signs 

 of wear, have them replaced by new ones. 



In the case of the unprepared sample, simply weigh the butter 

 which was transferred direct from churn or package to the tared 

 aluminum dish and record the weight thus obtained. In the case of 

 the prepared sample transfer a small portion, about 10 grams, of 

 the butter in the sample jar to the tared dish, weigh and record 

 weights. The butter is now ready for the evaporation of the mois- 

 ture. 



Heating: Slowly heat over flame or on hot plate, stirring con- 

 stantly with thermometer. When temperature has risen to 

 260 F. remove flame. The temperature will usually continue to 

 rise to about 280 F. When it has dropped back to about 240 F. 

 heat again as before. Evaporation of moisture then is complete. 

 Weigh the aluminum cup again and calculate per cent moisture. For 

 heating, use moderate heat. Too large a flame produces so intense 

 a heat that the contents are liable to sputter over and also may 

 become burnt. When using an alcohol flame, have a wire gauze or 

 light steel plate between flame and cup. When using a gas flame, 

 have a thin asbestos board between flame and cup. This helps to 

 give a more uniform heat. 



When the heating has been done properly, the curd in the bottom 

 of the cup should be slightly brown. A whitish yellow curd indi- 

 cates insufficient heating, which is conducive of too low tests. A 

 dark brown curd suggests overheating, which usually causes too high 

 tests. 



