FOODS — HUMAN NUTRTTTON. 563 



taiiu'd with milk iiowtlcr "would iiulit-ato that it is not as jjood a substitute 

 for fresh luilii as the tinned article." In making up rations the author suggests 

 that Ih lbs. of the evaiwrated vegetable should be considered a substitute for 

 the ordinary allowance of similar fresh vegetables. 



Concerning- preserved egg yolk, A. ScnooN.f.vNS (Bui. Soc. Chim. B<l<j., 

 22 (/.v«,S). i>i>. IJ!)-I22; abs. in Vhcm. ZcnfhI.. I'.iOS. I, \o. IS, p. /733).— Boric 

 acid was identified in jireserved egg yolk. 



Flour bleaching, II. Snvukk {Minnesota Sta. littl. Ill, pp. lOJ-l'/.S, figs. 3). — 

 The results of investigations of various questions related to the bleaching of 

 flour by o.xids of nitrogen are reported, including among others experiments on 

 the digestibility by healthy men of bread made from bleached and unbleached 

 flour, the character of the fat and gluten of bleached and unbleached flour, and 

 the distribution and occurrence of nitrites in food products. 

 Quotations from the author's summary follow: 



"The l)leafhing of flour is a natural process and takes place when flour 

 manufactured from well cleaned wheat is stored in thoroughly ventilated 

 warehouses. "With natural aging and bleaching there is a slight improvement 

 in bread-making value. 



"The coloring matter of flour is an inistable organic compound readily acted 

 uiion by heat, light, air, and a number of chemical reagents. It is mechanically 

 a.«sociated with the fat and gluten as an impurity. 



" None of the methods i)roposed for flour bleaching excejit the use of minute 

 amounts of nitrogen peroxid as that fienerated by the discharge of electricity in 

 the air, have survived the experimental stage. . . . 



"The fat from bleached and unbleached flour milled from the same wheat 

 is identical as far as iodin absorption number, nitrogen content, and heat of 

 combustion are concerned, no greater differences being observed between the 

 fat from the two flours than in the case of duplicate determinations on the 

 same sami)Ie. 



"The glutens from the bleached and unbleached flours are identical in 

 physical properties and show tlie same index of refraction. 



"The nitrogen pero.xid used in small amounts in the electrical bleacliing of 

 flour exerts no cliemical action upon the flour other than upon the coloring mat- 

 ter. The nitrogen peroxid appears to act in its well known capacity of carrier 

 of atmospheric oxygen, taking up oxygen from tlie air, oxidizing the coloring 

 matter, and again taking ui) oxygen from the air without itself entering into the 

 chendcal coniitosition of the flour. 



"Tlie nitrite reacting material in flour appears to be in pliysical rather than 

 chemical combination. When the flour is heated, the nitrite reacting material 

 imitarted by bleaching is expelled. All of the nitrite reacting material in the 

 gas emiiloyed for bleaching can be accounted for as soluble and volatile nitrites 

 in tlie flour and in the air surrounding the flour, leaving no nitrite reacting ma- 

 terial to chemically comliine witli the fat or gluten. When the bleaching gas 

 was lirougiit in contact with pure sand, with which it can not unite chemically, 

 the same amounts of nitries were absorbed as in the case of flour. 



" In tests where diflerent quantities of gas were usetl it was found that the 

 ani«iinit of nitrite reacting material left in the flour increased with the amount 

 of gas use<l up to a certain jioint, and that when a large excess of the gas was 

 ^enqiloyed then' was permanently ivtaiued in the Hour no more than when less of 

 the gas was usisl. 



" It was found tliat no relationship whatever existed betw»H'n the nitrite re- 

 acting material in the tlour and in the bread. Breads from both bleacluHl and 

 unbleai-hed Hours when liaked in a gas oven where there was |)oor Vi'utilation 

 contained the same aiiiixnit of nitrites. When the breads were properly made 



