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258 
Journal of Agricultural Research 
Vol. XXX, No. 3 
Fig. 4.—Spectrophotometric and colorimetric determinations, made at different times during the day, 
plotted to show the variations in the results by the two methods. The upper graph shows the results 
on the spectrophotometer, while the two lower graphs show the results for the colorimeter. The average 
for each method is also plotted 
