August 11, 1916] 



SCIENCE 



213 



ment made increasingly efficient by cooperation on 

 the part of the reputable producer and distributer, 

 who finds in the enforcement of these laws the 

 elimination of unfair competition. 



Preventing the Staling of Bread by Cooling in a 



Predetermined Atmosphere: Arnold Wahl. 



Bread and like products absorb while cooling a 

 considerable volume of gas from the atmosphere 

 in which it rests, due to a vacuum caused by the 

 physical condensation of the carbon dioxide in the 

 pores of the loaf and by the solution of carbon di- 

 oxide in the free water of the bread, the solubility 

 increasing as the product cools. Bread cooled in 

 an atmosphere of oxygen becomes stale in a few 

 hours while bread cooled in an atmosphere of car- 

 bon dioxide is so modified as to remain fresh for 

 several weeks, the reason being that in the former 

 case oxidation of the protein occurs similarly to the 

 effect of oxygen on the nitrogenous constituents of 

 beer, while in the latter oxidation is prevented. I 

 prefer to employ carbon dioxide freshly produced 

 by fermentation for this purpose, having been de- 

 termined by long experience in brewing to be best 

 suited to combine chemically with nitrogenous food 

 substances. 

 Use of Picric Acid in Meat Sugar Solutions: W. B. 



Smith. 



Proteoses, peptones and the greater portion of 

 the amino-acids are removed from meat extracts by 

 excess of picric acid combined with excess of phos- 

 photungstic acid in aqueous solution. More amino- 

 phosphotungstates are removed by adding hydro- 

 chloric acid to the filtrate. 



Little free hydrochloric acid remains, permitting 

 estimation of reducing sugar if quickly done. Ber- 

 trand's copper solutions and Low's iodid method 

 are used. Total sugar is determined after inver- 

 sion. 



Mercuric acetate, followed by phosphotungstic 

 and hydrochloric acids, gives the same results, but 

 removal of excess mercury is essential. Picric acid 

 does not interfere with reduction of Fehling's so- 

 lution. 



The Analysis of Maple Products VIII. The Appli- 

 cation of the Conductivity and Volumetric Lead 

 Subacetate Tests to Maple Sugar: J. P. Snell 

 and G. J. Van Zoeren. 



A representative sample of the sugar, say 100 

 grams, is dissolved in hot water, boiled to 219° P. 

 (103.9° C.) and filtered through cotton wool. The 

 resulting syrup is tested as directed in Papers VI. 

 and VII. Pure products give conductivity values 

 and volumetric lead values within the limits re- 

 ported for genuine syrups in Papers VI. and VII. 



Chinese Preserved Eggs — Pidan: Katharine 



Blunt and Chi Che Wang. 



Pidan is a kind of Chinese edible preserved eggs 

 made by covering fresh ducks' eggs by a pasty 

 mass of lime, wood ashes, salt and tea, and finally 

 rice hulls. It is solid, the yolk and white still sepa- 

 rate and very dark colored, and with remarkably 

 ammoniacal odor. The moisture of pidan yolk is 

 higher than that of fresh ducks' eggs, and of the 

 white very much lower, hence water has been trans- 

 ferred from the white to the yolk and lost to the 

 air. The ether extract of the yolk is low (only 21 

 per cent.) and its acidity high (8 per cent.). 

 The ash is high and alkaline. Coagulable protein 

 is lower than fresh hens' eggs, and, the most 

 marked change, ammoniacal nitrogen by Polin's 

 method is extraordinarily high (0.06 per cent, de- 

 termined on the filtrate from the coagulable ni- 

 trogen) . 



A Study of American Seers to show the Effects on 

 Their Composition of Various Eaw Materials 

 used in Their Production: L. M. Tolman and 

 J. G. Biley. 



DIVISION op agricultural chemistry 

 The Effects of Plant Foods upon the Amount and 

 Quality of Substances used for Foods, particu- 

 larly Fruit and Vegetables: H. A. Huston. 

 Does the Oxidation of Tetrathionate to Sulfur 

 affect the Accuracy of the Estimation of Thio- 

 sulfate by Means of Iodine? Philip L. Blumen- 



THAL AND S. D. AVERITT. 



In neutral or barely acid solutions, an excess of 

 iodine oxidizes tetrathionates to sulfates. Experi- 

 ments showed an oxidation of 18 per cent, of the 

 total sulfur in two weeks, with the excess of iodine 

 as 2:1. Whenever thiosulf ate is titrated with io- 

 dine, a small amount of sulfate is formed. This 

 does not cause an appreciable error when N/lO 

 solutions are used. In the analysis of lime-sulfur 

 solutions by iodine titration, the volumetric results 

 on thiosulf ate agree very closely with the value ob- 

 tained by oxidizing the tetrathionate with bromine 

 weighing as BaSd. The sulfate formation noted 

 might be due to presence of a little sulfite, but 

 there is reason to believe none is present. 



Separation and Estimation of Polysulfides and 

 Thiosulf ate in Lime Sulfur Solutions: S. D. 

 Aveeitt. 



The quantitative separation of polysulfides pre- 

 paratory to the determination of thiosulfate is ac- 

 complished by means of standard solutions of io- 

 dine or hydrochloric acid using appropriate indi- 

 cators. 



