[shutt-moloney] moisture-content OF FLOUR 



105 



of oxidation, since any further loss occurring in the second 5 hours 

 period in the vacuum oven (see Series A) would be more or less offset 

 if there were' any increase due to oxidation. Oxidation would imply 

 increase in weight and a consequent lowering of the apparent percent- 

 age of moisture. However, any oxidation which this series may indi- 

 cate must be very slight, the probable error affecting the results 

 being in the neighbourhood of • 1 per cent. 



Series A to D may therefore be considered as fairly conclusively 

 showing that the difference in results, comparing those obtained from 

 the vacuum oven with those of the air ovens, is not to be accounted 

 for by any oxidation of the flour. 



Having reached this point in the enquiry to account for the 

 difference in the results from the vacuum and air ovens, it was decided 

 to compare data obtained by heating 5 hours in the vacuum oven with 

 those obtained by drying to constant weight in the air oven, both 

 being at a temperature of 100°C. This experiment was planned with 

 the view of ascertaining the value of time as a factor in drying at air 

 pressures, and to learn if sufficiently protracted drying in the air oven 

 would yield the same percentage of moisture as that obtained by the 

 vacuum oven. 



Comparison of the Results from drying to constant Weight in Electric air oven at 100°C. 

 with those from drying 5 hours in Vacuum oven at 100° C. 



A study of the above data permits the following conclusions: 



1. That in the air oven at 100°C. constant weight was not reached 

 in less than 48 hours. 



2. That appreciably higher percentages resulted from drying 

 for 5 hours at 100°C in the vacuum oven than were obtained by drying 

 to constant weight for the same period in the air oven. 



Admitting the correctness of the finding in the foregoing para- 

 graph, it might be conjectured that if a sample of flour were dried in the 

 vacuum oven at 100°C., taken out and immediately placed in an riovena 

 at the same temperature an increase in weight would result, due to 



Sec. Ill.Sig. 8 



