THE FUSING POINT. 



Melting Points* 



33 



Another method described by Dr. Redwood, in a paper 

 read before the Society of Public Analysts, may, under some 

 circumstances, be found of use, as it needs only a drop or 

 two of the fat for each experiment. A small particle of the 

 melted fat is taken upon a glass rod and placed upon the 

 surface of some mercury, and allowed to congeal, the vessel 

 containing the mercury is placed into a water-bath, and a 

 slow heat is applied, the mercury, by virtue of its com- 

 paratively good conducting power, acquiring a uniform tem- 

 perature throughout, which is indicated by the thermometer, 

 and at the same time communicated to the fat. The fat, 

 when the temperature approaches its melting point, becomes 

 partially transparent, and if the stem or elongated bulb of 

 the thermometer be now brought up against it, the moment 

 fusion takes place the liquid fat will run into the channel 

 formed by the repulsion of the mercury and the outside of 

 the thermometer tube. Making use of this method Dr. 

 Redwood made the melting point of two genuine butters to 

 be respectively, " 80-5 F. and 81 -5 F. as their lowest, and 

 83-5 F. and 84-5 F. as their highest melting points." 

 * Proceedings of Society of Public Analysts, vol. i. p. 126. 



