CHAPTER XVI. 



THE ANALYSIS OF BUTTER FAT. 



Distillation Methods. 



Preparation of the Fat for Analysis. A portion of the 

 butter is placed in a beaker and melted by exposing to a tem- 

 perature not exceeding 50 C. (122 R). The water, with a 

 considerable amount of the other constituents, sinks to the 

 bottom, leaving the fat (containing, however, particles of curd 

 in suspension) as an upper layer. If the butter be genuine, fresh, 

 and well made, the melted fat will usually appear transparent ; 

 while if it be mixed with butter substitutes, rancid, or churned 

 at a high temperature, or if it has been melted and 

 re-emulsified, the fat frequently has a turbid appear- 

 ance. 



The fat, with as little as possible of the other 

 constituents, is poured upon a dry filter, which is kept 

 at a temperature sufficient to prevent the fat from 

 solidifying ; the clear fat, separated from all the other 

 constituents of butter, except a trace (0-2 per cent.) 

 of water and lactic acid, if present, is collected in a dry 

 vessel. It is sometimes of importance to prepare the 

 butter free from water. This may be done by shaking 

 it with a little calcium chloride (free from lime) and 

 filtering again. Chattaway proposes removing the water 

 by stirring in a number of pellets of filter-paper, which 

 have been dried in the water-oven. The author has 

 found that, so far as the proportions of the volatile acids, 

 insoluble acids and saponification equivalent are con- 

 cerned, the fat is entirely unaffected by this treatment, 

 Fig. 30. th u gh certain properties e.g.,, rise of temperature with 

 Stokes' sulphuric acid are slightly affected, owing to removal 

 Butter of the water. 



Clearing After filtration, the fat is cooled rapidly, so as to 

 Tube, prevent partial solidification and to ensure the homo- 

 geneous nature of the sample. 



Stokes' Fat- clearing Process. Stokes uses a tube open 

 at both ends (Fig. 30), the smaller and lower of which is closed 



240 



