THE ANALYSIS OF BUTTER 79 



scale where the standard solution should read, and a 

 key is provided for adjusting the scale to this. 



Detection of Sesame Oil. Add to 10 c.c. of the 

 melted butter o.i c.c. of a 2 per cent, alcoholic solution 

 of furfural, add I c.c. of strong hydrochloric acid, shake 

 well and add 10 c.c. of chloroform. A crimson colora- 

 tion of the aqueous layer indicates sesame oil. Some- 

 times coal-tar colours are added to the butter which 

 give a red colour with hydrochloric acid alone ; make 

 sure of the absence of these by testing a little of the 

 butter with hydrochloric acid. If these are present 

 use the fatty acids (p. 72) for the test. 



If furfural is not available dissolve o.i gramme of 

 sugar in 5 c.c. of hydrochloric acid, and shake with 



10 c.c. of melted fat. This will also give a crimson 

 colour with sesame oil. 



Detection of Cocoa-nut OiJ. Hinks' Method. Dis- 

 solve 5 c.c. of fat in 10 c.c.^of -ether, in a corked test- 

 tube, and pack this in ice ; after thirty minutes pour 

 the whole mass on a filter, and evaporate the filtrate ; 

 take up the fat with 3 to 4 c.c. of 96 to 97 per cent, 

 alcohol, boil when the fat should all dissolve, and cool 

 to 5 C. for fifteen minutes, and filter this ; cool the 

 filtrate to o C. for two to three hours. Place a little 

 of the cooled solution on a well-cooled slide, and 

 examine rapidly with a | or f in. objective. Butter 

 crystallises in round globular masses, while cocoa-nut 



011 gives characteristic feathery crystals, easily recog- 

 nised after a little practice ; other fats such as lard 

 give somewhat similar crystals. 



The Application of Analysis to the Solution 

 of Problems. The Detection of Adulteration. The Pre- 

 sident of the Board of Agriculture, under his powers 

 authorised by Clause 4 of the Sale of Food and Drugs 

 Act, 1899, has laid down the limit of 16 per cent, of 

 water in butter, and any quantity above this amount is 

 presumed to have been added. Occasionally water has 

 been worked into butter to add to its weight, but a 

 more frequent occurrence of excess of water occurs in 



