FLASK FOR DETERMITsTATION OF WATER IN FLOUR AND MEAL. 7 



quickly withdrawn, so as to see the height of the oil on the thermome- 

 ter, which should be so adjusted that the bulb will be three-fourths 

 of its length in the oil. 



(3) A moderate, steady flame should be kept, which will take 15 

 mmutes for the oil in the inner flask to reach 120° C, 26 minutes for 

 the entire test for corn meal, and 30 minutes for flour. If the oil is 

 hot between the two walls when the test is begun, the time required 

 to reach 120° with a proper flame will be less than 15 minutes. In 

 such instances the time from 120° to 150° C. should be approxi- 

 mately 6 minutes. 



(4) The thermometer should rise about 5 degrees C. in 1 minute, 



(5) After the flame is extinguished there is an increase of 10 to 

 15 degrees C. in temperature. 



(6) Before taking a reading the distillation flask should be dis- 

 connected from the condensing tube and all the moisture allowed 

 to collect in the graduate. 



(7) The outside flask can be corked while the inner one is being 

 emptied, and the same oil may be used five or six times before being 

 changed. 



(8) Cotton should be placed at the bottom of the funnel strainer. 



(9) The inner flask should be rinsed out with an extra 150 c. c. of 

 oil after it is emptied of the corn meal or flour. 



(10) Only special stoppers of the best quality should be used in 

 the necks of the copper flasks. 



(11) To insure accurate results when testing flour or meal a special 

 measuring graduate should be used. 



(12) For correct results the first run in new flasks should be dis- 

 carded and the results of the second one taken; also, if the apparatus 

 has not been used for several days, a second run should be made. 



ADDITIONAL COPIES of this publication 

 -l\- may be procured from tlie Supeeintend- 

 ENT OF Documents, Government Printing 

 GIFice, Washington , D. C. , at 5 cents per copy 



