5 



MILK AND DAIRY PRODUCTS PART 



flask is heated on the water-bath for about 8 hours, then it is 

 detached after being allowed to cool, the ether evaporated or 

 distilled off, and the flask, which now contains the fat, is dried 

 for 2 hours in the water-oven at 100 C. The flask is taken 

 out at the end of this time, allowed to cool in a desiccator, and 



FIG. 17. Soxhlet's Ball Condenser 

 (cross section). 



FIG. 18. S'torch Condenser 

 for Use with the Extrac- 

 tion Apparatus. 



then weighed. On deducting the weight of the empty flask, 

 the weight of fat is obtained. 



This method gives very good results with ordinary, that is 

 whole, milk, and has long been regarded as the standard method 

 for the estimation of the fat in milk. 



(b) Nilson's Kaolin Method. 



Professor L. F. Nilson of Stockholm l introduced in 1891 the 

 use of granular ignited kaolin as a substance on which to 

 dry the milk. The grains of kaolin must be 0'5 1'5 mm. in 

 size, and 25 30 g. of this material will go into one of the fat- 

 free extraction cartridges made by Schleicher and Schull. 

 (Latterly aluminium cartridges have come into use for this 

 purpose.) About 10 g. of milk are weighed from a small beaker 

 or flask in the usual way, the milk being poured over the kaolin 

 in the cartridge. The kaolin absorbs all the milk, so that the 

 walls of the cartridge are not wet. The cartridge with its 

 contents is then dried for 2 hours in the water-oven, and 



1 Kungl. LajidtbruksakademieiM Handl och Tidskrift, 1891 Chem 

 Zeitung, 1891, No. 37. 



