CHAPTEE V. 



THE ANALYSIS OF BUTTER-FAT. 



Previous to the publication of tlie first edition of this book 

 in 1874, very little was known about the composition of the 

 fat of butter, and very few attempts seem to have been made 

 to arrive at a scientific solution of the question — Is butter 

 chemically different from other fats, and can it chemically be 

 distinguished from them ? Upon the physical differences 

 between butter and its fatty relations — ^namely, colour, smell, 

 melting point, solubility in ether, alcohol, and petrolexun 

 spirit, power of turning the plane of polarisation, etc.— many 

 methods had been based to detect admixture of the cheaper 

 fats with the more valuable one ; but though some of these 

 methods were not without value, none could be regarded as 

 a safe guide for the analyst, whilst some were positively 

 dangerous, because more calculated to mislead than to poiat 

 out the truth. 



" During the last two years, however, the subject of butter 

 has been much worked at, and its analysis is now as well 

 understood, and as certain, as any other process in the whole 

 range of food analysis." * We cannot yet, as will be seen 

 in the following pages, with certainty speak as to the con- 

 stitution of butter-fat, but as far as the detection of 



^ * Analyst, August, 1876. 



