shutt-moloney] MOISTURE-CONTENT OF FLOUR 



103 



To obtain further and more direct evidence as to the possible 

 oxidation in flour, samples were dried to constant weight in a stream 

 of dry hydrogen and afterwards in a stream of dry air. The hydro- 

 gen and air were dried by bubbling through strong sulphuric acid, 

 the constancy of the stream being under control and carefully regu- 

 lated. The results obtained by this method, using the water oven, are 

 given in the following table: 



Flour dried in current of dry hydrogen and subsequently in stream of dry air in Water 



oven at 95° C. 



In hydrogen. 



In air, following. 



Time 

 in hours 



10-7 

 27-0 

 31-7 



10-5 



Percentage of Moisture 



13-14 

 13-30 

 13-28 



13-28 



13-09 

 13-22 

 13-16 



13-20 



13-26 

 13-18 

 13-26 



13-27 



It is obvious that these results furnish no evidence of oxidation. 



The next step in this enquiry as to possible oxidation was to 

 compare results obtained in a stream of dry hydrogen in an air oven 

 with those obtained in the vacuum oven at 100°C. The data are as 

 follows: 



Flour dried in current of dry hydrogen at 95° C. and in vacuum oven at 100° C. 



These results conclusively show that no oxidation of the flour 

 occurs in the vacuum oven at 100°C. It will be noted that the per- 

 centages from the vacuum oven are slightly the higher, due no doubt 

 to the somewhat higher temperature employed. 



Having obtained satisfactory evidence that no appreciable 

 oxidation of the flour took place on drying in the vacuum oven at 

 100°C. for 5 hours, it was decided to adopt this method as a "standard" 

 for the purpose of comparison. 



