30 



ANALYSIS AND ADULTERATIONS OF BUTTEE. 



The method employed by Dr. Hassall * i3 a modification 

 of the plan described, great precautions being taken to ensure 

 correctness of the result. Instead of a weight, he employs a 

 small glass bulb, having a weight of 0-18 gramme and a volume 

 of about 0-5 c.c. This is placed in the bottom of a test tube, 

 one-third of an inch wide, and four inches high. A little 

 melted fat is poured upon the bulb, and is allowed to cool to 

 keep the float in its position ; the tube is then filled with the 

 fat, and a thermometer, graduated in tenths of degrees C, is 

 introduced into the fat in test tube, not into the water 

 surrounding it. The fat is solidified by immersion in water 

 of 13-3° C. for an hour. The test tube is then suspended in a 

 large beaker filled with cold water, and this in its turn 

 heated in a water bath. Thus the temperature rises very 

 slowly and evenly. As soon as the fat is sufiiciently soft, the 

 bulbs begin to rise ; this Dr. Hassall calls " the rising point." 

 The fat gets clear very soon afterwards, the point of clearance 

 being also noted. 



The following results were obtained by Dr. Hassall : — 



Points of Fusion and of Clearance of Butter. 



It will be noticed that the " point of clearance " exactly 

 coincides with our " sinking point." 



* "Food and its Adulteratione," p. 441. 



