Butter AToisti' re-Tests. 525 



the paper, into the flask, and add 6 c.c. of an amyl reagent. This 

 reagent consists of a mixture of amyl acetate and amyl valerinate. 

 It serves a twofold purpose : First, it prevents the butter from foaming; 

 second, it has a high boiling point, and after nearly all of the moisture 

 is expelled from the sample .the reagent begins to boil and drives off 

 any last traces of moisture. After the reagent is added, the sample 

 is heated over an alcohol lamp or a gas jet. If the sample sputters 

 or foams more than it should, 2 or 3 c.c. more of the amyl reagent may 

 be added. The water is driven off in the form of vapor, condenses in 

 the graduated tube, and runs back into the bulb at the lower end of 

 the tube. This condensation is aided by cold water which is placed 

 in the water-jacket before the sample is heated. Care must be taken 

 not to heat the contents of the flask too rapidly, or the moisture will 

 escape in the form of vapor from the upper end of the condensing tube. 

 The directions are not to allow the vapor to rise above the 15% mark 

 on the graduated tube or some of the moisture may be lost. Care must 

 be taken to have open the stopper at the upper end of the tube while 

 heating the sample. If this is not done, the vapor will collect and 

 burst the apparatus. 



When the contents of the flask turn dark brown and the crackling 

 noise ceases, the moisture is supposed to be entirely driven off. The 

 condenser is then removed from the flask, the upper end of the tube 

 closed, and the apparatus inverted. This allows the water in the con- 

 densing jacket to run out, and the moisture from the sample which 

 is collected in the bulb to flow into the graduated part of the condensing 

 tube The outside cylinder which forms the walls of the water-jacket 

 may now be removed, or not, as desired. The writer finds it most con- 

 venient to remove the cylinder at this time. After making sure that 

 the stop-cock or ground glass stopper is securely in place, the water 

 and amyl reagent are forced into the graduated part of the tube by 

 raising the condenser high in the air at arm's length and giving the 

 apparatus a vigorous swing downward. Care must be taken not to 

 raise the apparatus so high that the water will flow back into the bulb 

 at the bottom of the tube. This swinging motion is repeated several 

 times. The water is considerably heavier than the amyl reagent, and 

 will go to the bottom of the graduated tube. There is a distinct line 

 between the amyl reagent and the water. The moisture may now be 

 read directly in percentages, since the graduated tube is made to read 

 directly in percentages when ten grams of butter are taken. If more 

 or less than ten grams of the sample are used, a corresponding correc- 

 tion must be made. 



