PER CENT OF FAT IN BUTTER 107 



Determination of the Per Cent of Fat in Butter. The methods 

 for the determination of the per cent of fat in butter may be 

 classified under two heads, viz., 



(1) Scientific methods, such as 



(a) The Extraction method. 



(b) Rose-Gottlieb method. 



(c) Indirect determination of fat. 



(2) Practical methods, such as 



(a) The 90 per cent bottle designed by Hepburn for use 

 in the Babcock test. 



(b) The Shaw test. 



Scientific Methods. The scientific methods are too com- 

 plicated and require too long a time for their completion to be of 

 practical use in a creamery. 



The Rose-Gottlieb method may be briefly outlined as follows: 



This method, which was originally designed for the estima- 

 tion of fat in milk, can be used with advantage also for the deter- 

 mination of fat in butter. 



According to A. Hesse, 1 about 2 grams of butter are weighed 

 out into a 3 cm. long, half -cylindrical glass tube, or simply 

 wrapped in a piece of stiff fat-free paper of the same form. The 

 tube or paper and the contained fat are then introduced into a 

 Gottlieb cylinder, and hot water is added until the lo-cm. mark 

 is reached. If the butter .does not melt, the cylinder is placed in 

 warm water until it does. Then i c.c. of ammonia and 10 c.c. 

 of 95 per cent alcohol are added, exactly as in the estimation of 

 milk-fat. If the mixture is still warm, the cylinder is cooled in 

 cold water so that the ether which is to be added will not evap- 

 orate too quickly. The cooling must not, however, be carried 

 too far; otherwise the butter will become solid again. Twenty- 

 five c.c. of ether are then added, and the contents of the cylinder 

 mixed by repeatedly inverting it. Afterwards 25 c.c. of petro- 

 leum ether are added and the mixing repeated. 



After the different layers have separated quite sharply from 

 one another, the clear ether-fat solution is siphoned off in the 

 usual way, the lower opaque layer not being disturbed. Then 



1 Molkerei-Zeitung, Hildesheim, 1903, No. 27. 



