Nov. is, 1920 Changes Taking Place in the Tempering of Wheat 273 



the total moisture content up to the desired percentage. The bottle was 

 corked tightly and the mixture was well shaken. The bottle was then 

 placed in the thermostat, which had been brought to the desired tem- 

 perature, and the mixture was allowed to remain in the thermostat for 

 the desired length of time. At the end of the time the wheat was ground 

 as rapidly as possible in the mill. The mill was set to grind to the same 

 fineness for each lot of wheat, and each lot was put through the mill the 

 same number of times. During the grinding the milling qualities were 

 judged as nearly as possible, and after grinding the yields of straight 

 flour were calculated. 



Sufficient flour to equal 50 gm. on a moisture-free basis was imme- 

 diately weighed out. This was placed in a fruit jar, and sufficient dis- 

 tilled carbon- dioxid-free water was added to make the ratio of moisture- 

 free flour to water 1 to 10. This water had been previously heated to 

 40 C. To this mixture 2 cc. of toluene were added as a preservative, 

 the jar was tightly closed by means of a rubber and a screw cap, and 

 the contents were thoroughly mixed by shaking. The jar was then 

 placed in the thermostat, where the temperature was 40 C. The flour 

 was extracted for 2 hours at this temperature, the jar being well shaken 

 every 15 minutes. At the end of 2 hours the jar w r as removed and the 

 contents were poured into a centrifuge cup. The cup was then placed 

 in the centrifuge and whirled for 5 minutes at a speed of 2,500 revolu- 

 tions per minute. Finally the supernatant liquid was poured through a 

 folded filter, and the filtrate was used for the determinations of hydrogen- 

 ion concentration, total acidity, water-soluble phosphorus, and titrable 

 nitrogen. For the determination of the hydrogen-ion concentration and 

 total acidity 100 cc. of the filtrate were pipetted into an electrode vessel. 

 The vessel was then placed in the hydrogen-ion apparatus, and hydrogen 

 gas was passed through until the potential remained constant (within 

 1 millivolt) for 15 minutes. During the entire time the vessel was shaken 

 60 times per minute. After this constant potential was noted, N/10 

 alkali was run in from a burette in small portions at a time until the 

 constant potential indicated a P H value of 7, which is the absolute neutral 

 point. The number of cubic centimeters of N/10 alkali used were then 

 taken to represent the total acidity. 1 



The water-soluble phosphorus was determined from a second 100-cc. 

 portion from the same filtrate. The phosphorus was determined by the 

 usual method after the organic matter had been destroyed by boiling 

 with nitric acid. The titrable nitrogen was determined in a third 100-cc. 

 portion by the formaldehyde method of Sorensen, using thymolphthalein 

 as an indicator. The number of cubic centimeters given in Table I 

 multiplied by 1.4 gives the number of milligrams of titrable nitrogen 

 in 100 cc. of the extract. 



For a control, a portion of each variety of wheat, untempered, was 

 ground, and an extract was made of each in exactly the way described 



1 For fuller description see Swanson, C. O., and Tague, E. L. op. cit. 



