126 
IOWA ACADEMY OP SCIENCE 
larger ones did so. He did not try the digestibility of the bleached fionr 
alone, however. An application for an injunction to prevent the prohibi- 
tion of the sale of bleached fionr in North Dakota was denied, not 
because there was proof that the fionr was injurious to consumers but 
because the statute forbidding the addition of any antiseptic materials 
If 
to food-stuffs was broad enough to include the nitrite reacting material 
formed in the flour during the bleaching. After a hearing in AA^ashing- 
ton. Secretary of Agriculture AA^ilson has decided that bleached flour 
cannot be an article of interstate commerce. Recently Halliburtoid has 
reported a lessened digestibility of fionr products due to the bleaching 
agent. 
On the other hand, Alway" and Snyder" found that in the bread-rais- 
ing and baking process practically all the nitrite reacting substance 
disappeared from the bread if yeast is used. AVesener and Teller" showed 
that in their experiments there was no difference in the digestibility of 
the bread from bleached and unbleached flour, a conclusion at which 
Snyder also arrived. , • 
In the experiments reported below tests have been made on the diges- 
tion of the starch of the cooked flour by the ptyalin, of the peptic diges- 
tion of moist gluten and of bread, and of the digestion of the starch of 
cooked flour and of uncooked dry gluten by the pancreatic ferments. 
In all cases the flours used were from the same mill, one being bleached 
and the other being unbleached. The same amount of flour and digestive 
solutions were used for each test, the two samples being treated side by 
side under the same conditions. 
SALIVARY DIGESTION. 
AA^hile in parallel tests the amount of flour was the same in the bleached 
and unbleached sample, in different series the amount was varied, but 
was generally from two to four grams of flour, boiled with water and 
diluted to a liter. A measured volume of saliva was added with a few 
drops of a solution of iodin in potassium iodid and the two samples 
were kept in a constant temperature water bath at 38 degrees. The 
progress of the digestion was judged by the change of color from a 
deep blue through a violet and reddish to a colorless — what Halliburton 
calls the achromic point. Table .1 gives some of the typical results. 
'‘Halliburton, Journal of Hygiene, September, 1909. 
‘^^Alway, Bulletin of the Agricultural Experiment Station of Nebraska, Vol. 
XX, Article HI, October, 1907. 
Anyder, Bulletin JII. Agricultural Experiment Station, University of Minne- 
sota. August, 1908. 
WVesener and Teller. Journal of Industrial and Engineering Chemistry, 
I 700. October, 1909. 
