52 DAIRY LABORATORY GUIDE 



manufacturers, to eliminate this danger of using a 

 tube with a stopper which has not been ground to 

 fit. The tube C is graduated after the stopper F is 

 ground in, the zero mark being the end of the stop- 

 per. Each mark of the graduation represents one- 

 fiftieth c.c, or when a 10-gram sample of butter is 

 used each mark represents two-tenths of 1 per cent 

 of water. E is a, glass condensing jacket connected 

 to the graduated tube C by rubber stopper D, as 

 shown in figure 35, or ground onto the bulb of the 

 tube C at the point D, as shown in figure 34. The 

 apparatus shown in figure 1, having the condensing 

 jacket connected by means of a rubber stopper, is 

 the form which seems most satisfactory for general 

 use. 



Rubber Stoppers. The rubber stopper B will be 

 slowly decomposed by the heat and reagent during 

 the process of making the tests. As a stopper is 

 rendered unfit for use by making about one hundred 

 determinations, extra rubber stoppers should be 

 obtained. 



Reagents 



Amyl Reagent. A mixture of amyl acetate 5 

 parts and amyl valerianate 1 part. Must be free 

 from water-soluble impurities in order to give accu- 

 rate results. Users not in position to test this 

 reagent for impurities should insist on a tested 

 article. 



Alcohol (for burning) when alcohol lamp is used. 



