54 



MILK AND DAIRY PRODUCTS PART 



average, are 0*03 per cent, for separated milk, and for butter- 

 milk more, sometimes as much as O'l per cent. The reason for 

 this lies simply in the fact that in the latter cases the fat is in 

 a very finely divided state, and so cannot be extracted completely 

 after drying on some porous material. 



L. F. Rosengren 1 has shown that the fat obtained in the 

 Rose-Gottlieb method always contains a little lecithin and 

 gives an opalescence on redissolving in pure ether ; the amount 

 of lecithin is, however, so small as to be negligible. 



For separated milk and buttermilk, Gottlieb's method is the 

 best and most exact. M. Weibull, 2 who from the beginning 



advocated its use, has shown 

 that the results with separated 

 milk and buttermilk, where 

 the samples are analysed by 

 different chemists, are the most 

 reliable that can be obtained 

 by any method. 



When analysing cream, 3 3 

 to 5 g. are weighed from a 

 small covered beaker into the 

 Gottlieb cylinder, and the 

 beaker again weighed. The 

 cream in the cylinder is then 

 diluted with water to exactly 

 10 c.c., and the determination 

 made as for milk, save that as 

 much as possible of the ethereal 



solution of fat should be drawn off, the cylinder again made up 

 to its previous volume with ether-benzine (the distillate from a 

 previous experiment serves very well), thoroughly shaken, and 

 this second quantity syphoned off into the same flask. In this 

 way the weight of fat which is left expresses all that was in the 

 sample of cream. 



K. Farnsteiner has designed a special form of tube for the 

 Rose-Gottlieb method. The lower and middle parts of it are 

 widened out, whilst that which lies between and carries the 

 1 Ref. p. 51. 



- Milch- Zeitung, 1898, p. 406 ; Chem. Zeitung, No. 63. 



' A. Hesse, Molkerei- Zeitung (Hildesheim), '1902, p. 49 ; M. Siegfeld and 

 M. Popp,ibid., 1903, No. 13. 



FIG. 19. Farnsteiner's Tube for the 

 Gottlieb Method. 



