122 MODERN METHODS OF TESTING MILK 



as vapor into the graduated tube, where it is con- 

 densed, and then runs back into the receiving-bulb 

 (C). The condensation in the graduated part of the 

 tube must be carefully watched and the steam not 

 allowed to go higher than the 15 cc. mark, in order 

 to avoid risk of losing water. If it goes above this 

 mark, remove the flask from the flame for a short time. 

 If the mixture in flask A shows a tendency to foam 

 over, remove the flame. In case of persistent foam- 

 ing, cool the flask and contents, add about 2 cc. more 

 of amyl reagent and continue heating. When the mix- 

 ture in the flask becomes brown and all crackling 

 noise ceases, the water has all been driven from the 

 flask. This usually requires 5 to 8 minutes. (6) 

 After completing distillation, flask A is disconnected 

 from stopper B and the glass stopper G is firmly in- 

 serted in end of graduated tube. (7) The tube is 

 then inverted, transferring the water from the receiv- 

 ing-bulb (C) into the graduated tube, care being 

 taken not to allow any water to be lost through the 

 small bent tube inside the bulb. The water is then 

 poured from the condensing- jacket, after which the 

 jacket may be removed. (8) Some amyl reagent is 

 distilled with the water, but is easily separated as fol- 

 lows: Hold the receiving-bulb in the palm of the 

 hand and the stoppered end away from the body; 

 then raise to a horizontal position and swing at arm's 

 length sharply downward to the side. This is re- 

 peated several times until the line of separation be- 

 tween the water and amyl reagent is sharply distinct, 

 the amyl reagent rising above the water. The tube 

 should then be held a short time with the sto4 



he tube 



** 



