i88 MILK AND DAIRY PRODUCTS PART 



well mixed in the usual way, is weighed into an ordinary Gottlieb 

 tube without foot (Palmquist describes a special form of tube 

 with a bulb-like extension at the lower end, but the ordinary 

 tubes are just as suitable). The cheese is then treated with 

 10 c.c. of 2'5 per cent, ammonia, and, by warming on the water- 

 bath and shaking, a milky homogeneous solution is obtained, to 

 which, after cooling, 10 c.c. of alcohol are added. After shaking, 

 25 c.c. of ether are added and the tube again shaken, after which 

 25 c.c. of petroleum ether are introduced. The tube must 

 again be well shaken and inverted before being left to 

 stand. Two sharply defined layers separate out, as in the case 

 of milk, and after a few hours the clear ethereal solution of fat 

 is syphoned off as completely as possible into a tared flask, care 

 being taken that none of the cloudy lower layer passes over. 

 A further 25 c.c. ether and petroleum ether are then added, the 

 contents well mixed after each addition, and finally left to 

 separate out. The ethereal solution is syphoned off into the 

 the same flask as before, the ether evaporated off, and the fat 

 dried and weighed as usual. 1 



This method gives most excellent results even with skim 

 milk cheese, and is undoubtedly the best known method for the 

 determination of the fat in cheese ; it is also very simple and 

 easy to carry out. 



M. Weibull 2 has recently improved Palmquist's modification of 

 the Gottlieb method, so that it is now almost identical with that 

 used for milk, which must be regarded as a great advantage. 

 The cheese is finely ground up, and T03 g. are placed in the 

 bottom of a Gottlieb tube and 10 c.c. of ammonia (the strength is 

 of no importance) added. By shaking the tube and gradually 

 warming it in a water-bath to a temperature of 75 C., the 

 cheese is brought into solution. If this is not accomplished in 

 half an hour, 10 c.c. of 95 per cent, alcohol are added, and the 

 liquid again well shaken and allowed to stand at 75 C. In 

 ordinary cases when the temperature has reached 75 C., the 

 tube can be allowed to cool, and then 10 c.c. of alcohol added and 

 the ordinary Gottlieb method followed. When syphoning off, 

 1'5 c.c. of the clear ethereal solution is allowed to remain 



1 Palmquist only takes an aliquot part of the ether-fat solution, and calcu- 

 lates from it the weight of the total fat contained in the cheese. In the above 

 method all the fat is obtained together in the flask. 



2 Zeitschrift filr Unt. d. Nahr. und Genussmittel, 1906. Ibid., 1909. 



