226 



MILK AND DAIRY PRODUCTS PART 



corresponding normal acids. Orla Jensen found the folio wing- 

 proportional numbers for butyric, valeric acids and their 

 isomerides : 



The proportional numbers for normal butyric acid and iso- 

 valeric acid agree with those given by Duclaux for the same 

 acids. As is seen, the figures relating to the normal acids are 

 considerably lower than those for the corresponding " iso " 

 acids, so that Duclaux's method can serve to separate an acid 

 from the " iso " acid, and for this purpose is the best method 

 when a single acid in a pure state is in question. 



3. Alcohol 



In the normal spontaneous decomposition of milk, little or no 

 alcohol is formed, but where a special fermentation takes place, 

 as with koumiss or kephir, considerable quantities may arise. 



The test usually employed, or at least usually recommended, 

 for the detection of small quantities of alcohol, is the iodoform 

 test. The filtered milk is made alkaline with milk of lime, 

 100 c.c. distilled, and the first 10 c.c. of the distillate warmed 

 in a test-tube in the water-bath to 60-70 C. A little caustic 

 soda and a few grains of iodine are then added, excess 

 of alkali being avoided, as it makes the test less sensitive. 

 After the tube has been well shaken to dissolve the iodine, it is 

 cooled, and the presence of alcohol is denoted by a yellow pre- 

 cipitate of iodoform. This precipitate can be identified by the 

 characteristic iodoform smell, and by the microscopic examina- 

 tion in which the iodoform crystals are seen to be regular 

 hexagonal flakes. 



