THE MOJONNIER TEST 291 



POWDERED MILK AND MALTED MILK 

 Method of Sampling 



Mix the sample thoroughly, making sure that it is sufficiently 

 pulverized and representative of the entire lot to be tested. Trans- 

 fer the pulverized sample promptly to a sealed jar. Mix before 

 removing portions for testing. 



BUTTER FAT DETERMINATION 



(1) Weigh out rapidly, to prevent absorption of moisture 

 from the air, about one gram of milk powder into butter boat. In 

 case of malted milk, weigh out a 0.5 gram sample. 



(2) Add 8.5 c.c. of hot water to flask. Insert cork. Heat 

 flask in water boat and shake thoroughly until the sample is well 

 mixed. 



(3) Add 1.5 c.c. (one charge) ammonia, and shake thor- 

 oughly- 



(4) Add alcohol up to line on small neck of flask. Insert 

 cork. Replace flask into flask holder. Shake flask thoroughly with 

 cork inserted. Use best quality cork only. 



(5) Cool flask by running cold water over lower end of ex- 

 traction flask, if flask is very hot. This is not ordinarily necessary. 



(6) Add 25 c.c. ethyl ether. Insert corks, shake vigorously 

 until all butter is dissolved out of boat. Then add 25 c.c- petroleum 

 ether and repeat operation. 



(7) Centrifuge flasks, turning handle thirty turns after cen- 

 trifuge has reached a speed of about 600 R. P. M. 



(8) Pour off extractions into proper weighed 3^-inch alum- 

 inum dishes. Repeat above extraction, adding first alcohol, then 

 25 c.c. of each ether. Excepting for very accurate work a third 

 extraction is not necessary. 



The second extraction will remove all but .10 to .15 per cent 

 of the butter fat. For factory control work this would be a good 

 margin of safety. 



(9) Evaporate off ether at 135 degrees C. on "fat plate," and 

 when all of ether is off, dry fat in fat oven held at 135 degrees C. 

 for five minutes after the vacuum has reached at least twenty-two 

 inches. 



(10) Cool, weigh and calculate per cent butter fat. 



