614 



SCIENCE 



[N. S. Vol. LII. No. 1356 



tions, and on all kinds of catalytic reactions in 

 pure and industrial arts. In beef-broth-peptone 

 media, for example, the glycerophosphates do not 

 give the troublesome precipitates formed by phos- 

 phates, and can therefore be added in the form 

 adjusted sterile tablets or solutions to warm ster- 

 ile media^ with or without agar; the resulting 

 medium is buffered, adjusted, clear and sterile 

 for immediate use. The glycerophosphates can be 

 sterilized in solid or liquid condition without ap- 

 preciable decomposition. Similar reports will soon 

 be made on other carbohydrate phosphates. 

 , Hydrogen electrode measurements of the acid 

 and hasic ionization constants of asparaginic acid 

 and its value as a buffer and nutrient material in 

 culture media: J. H. Hoppield, J. B. Halstead, 

 Marguerite A. Brennan and S. F. Agree. The 

 hydrogen ion concentrations of solutions of M/5o 

 asparaginic acid vary from lO-ie to IO-12 when the 

 asparaginic acid is treated with acid and alkali 

 varying from two mols of the former to three 

 mols of the latter. Between Ch = 10-5 and 10-9 

 there is a sharp inflection in the titration curve 

 because of the completion of the neutralization of 

 the stronger acid and the beginning of the neu- 

 tralization of the second carboxyl. From the com- 

 plete titration curve and the ionization values of 

 the salts the constants Km :^ 1.1 X 10-*, Ko2 = 

 1.4 X 10-10 and Kb = 1.2 X IO-12 are calculated. 

 These are in good agreement with the values of 

 Kai and Kb obtained by conductivity, catalysis 

 and hydrolysis methods. The value of Kaj is new 

 and is lower than the value of Ka = about 10-^ for 

 asparagin, as expected for an acid salt. In 

 another article we have shown that the inflection 

 curves of asparaginic and phosphoric or pyropho- 

 sphoric acid mutually annul each other, and make 

 such mixtures very fine buffer materials as well as 

 nutrients in media for bacteria and fungi. 



The nitrogenous constituents of condensed milk 

 as compared with fresh milk: A. W. Homberger 

 and B. Mathin. 



Tlie buoying up of the equilibrium of milk salts 

 during meat treatment: Harper F. Zoller. The 

 precipitation of calcium from solutions of milk 

 salts, prepared in accordance with the composition 

 and concentration occurring in the average of nor- 

 mal cows milk and at the reaction of normal milk, 

 was followed quantitatively and with the hydrogen 

 electrode during the effect of temperature. The 

 loss of calcium was progressive with the time and 

 intensity of heat treatment. The hydrogen ion 

 concentration proportionately with the removing 



of the buffer material (phosphates) by the cal- 

 cium. Doubling the quantity of citrates above 

 normal although not changing the initial pH of the 

 solutions greatly reduce the precipitation of the 

 calcium phosphate and at the same time main- 

 tained a higher final pH*. Lactates and malates 

 acted likewise. This serves to aid in explaining 

 how the lactic souring of milk may increase its 

 stability towards heat. 



Hydrogen electrode study of the curdling in 

 casein solutions at high temperatures: Harper F. 

 Zoller. When solutions of pure Hammarsteu 

 casein in carbonate free NaOH or KOH are heated 

 in sealed tubes to temperatures ranging from 

 118° C. to 135° C. a precipitation of curd takes 

 place, the formation of which is dependent upon 

 the hydrogen ion concentration and the duration of 

 heating. The casein solutions contained no cal- 

 cium. All of the caseinate solutions remained clear, 

 whose initial hydrogen ion concentration is less 

 than 3.16 X 10-t, (pH 6.5) although the solutions 

 had been heated to 135° C. for forty minutes. 

 There is a regular heating period of from 0.18 to 

 0.54 pH corresponding respectively to solutions of 

 initial pH of 5.78 and 8.26. The precipitated curd 

 is soluble in acids and alkalies and resembles the 

 curd made from sterilized milk or milk heated to 

 high temperatures as described by the author in a 

 previous communication. The term /3 casein is 

 suggested for this product to differentiate it from 

 the products obtained by Lacquer and Sackur from 

 dry casein. The significance of this phenomena in 

 connection with the coagulation in evaporated milk 

 is discussed. 



Chemistry of digitalis: H. C. Hamilton. 



Charles L. Parsons, 

 Secretary 

 (To be continued) 



SCIENCE 



A Weekly Journal devoted to the Advancement of 

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 ceedings of the American Association for 

 the Advancement of Science 



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