TESTING SKIM-MILK, WHEY, CHEESE, ETC. 87 



operation requires 15 to 20 minutes. The principle of 

 the test depends on the separation of water from but- 

 ter by distillation in the presence of a slightly volatile 

 mixture of high boiling point which does not -mix 

 with water. The apparatus will be furnished by 

 dairy-supply houses. 



Apparatus. The following apparatus is required 

 for the test: 



1 i ) Balance and weights. A cream-testing bal- 

 ance (see p. 72), sensitive to 0.025 gram; and two 

 weights, one 5-gram and one lo-gram. 



(2) Graduate. Measuring 6 cc. 



(3) Burner. A gas burner or an alcohol lamp. 



(4) Paper. Parchment, perfectly dry, 5 by 5 inches 

 in size. 



(5) Special testing apparatus. This includes three 

 essential pieces, (a) a flask (A Fig. 36a) holding 

 about 70 cc., (b) a receiving bulb with graduated tube 

 (C Fig. 36a), and (c) a condensing jacket (E Fig. 

 36a). The receiving bulb is connected with flask A by 

 means of a rubber stopper (B). G is a ground glass 

 stopper fitting tightly into the tube above the gradu- 

 ated scale. Each stopper and tube should be marked 

 so that each stopper shall always be used with its cor- 

 responding tube. The graduation of the tube is done 

 after the glass stopper is fitted, so that the zero mark 

 is the end of the stopper. Each mark of the graduated 

 scale represents 0.2 per cent, of water when a lo-gram 

 sample of butter is used. The glass condensing jacket 

 (E Fig. 36a) is connected to the graduated tube by a 

 rubber stopper (D Fig. 36a). 



