34 ANALYSIS AND ADULTERATIONS OF BUTTER. 



Mr. Bell takes the melting point in the following simple 

 manner : " A small portion of the fat, which had a somewhat 

 vitreous appearance, was taken up on the loop of a platinum 

 wire and introduced into a beaker of water placed in a 

 porcelain dish, and the loop brought close to the bulb of a 

 thermometer. The temperature of the water was slowly 

 raised and the temperature read off immediately the fat 

 assumed the liquid condition." (See tables, page 76.) Mr. 

 Bell gives the fusing point at about 32 C. * 



Some interesting facts with regard to the well-known 

 curious allotropic conditions through which butter and 

 other fats may be made to pass by the application of 

 heat, in certain definite degrees, was pointed out by Mr. 

 Patrick Duffey, in a letter published in Chemical Neios and 

 reprinted in the Proceedings of Society of Public Analysts, 

 page 168, in which it is shown that butter, pork, and mutton 

 fats are capable of assuming at least two distinct allotropic 

 modifications, between which there is a third but less marked 

 condition, which might be a mixture of the other two. Each 

 of these different conditions has a separate fusing point ; for 

 the purpose of identification they were designated first, 

 second, and third, according as they were at the first, second, 

 or third of these points. 



Mr. Duffey declares that "if a specimen of butter, the 

 second melting point of which lies at 31 '2 C., be heated to 

 60, and then solidified by a powerful exposure to a tem- 

 perature not exceeding 14 or 15, it will melt at 17. This 

 melting is most readily made visible by plunging a capillary 

 tube containing a portion of the substance into water at that 

 temperature. If the substance be now kept at the range of 

 temperature from 17 to 20, it solidifies, and in doing so 

 passes more or less completely into an allotropic modifica- 



* " Determination of the Melting Points of Butter and other 

 Pats." Proceedings of Society of Public Analysts, p. 51. 



