November 17, 1922] 



SCIENCE 



579 



hydroquinone systems, is not sufficient to cause 

 any perceptible drift in the values of J|o at least 

 in acid solution when the latter is determined 

 over a wdde range of concentrations by the method 

 of Clark, the concentration of the quinone sub- 

 stances varying between .001 to .003 M. Impuri- 

 ties whose potentials approximate that of the 

 system under examination so closely as to evade 

 detection by differential titration cause pro- 

 nounced drifts, the extent of which depends upon 

 the amount of impurity present as well as 

 whetlier the impurity has the higher or lower 

 potential. 



Electrometric titrations of silicic acid: "William 

 Sterioker. Silicic acid was titrated with sodium 

 hydroxide in order to determine wdiat salts it 

 formed. The sol was prepared from 'recrystallized 

 sodium metasilicate and was carefully purified by 

 dialysis. The pure sol gelled readily. There was 

 no indication of the presence of hydrogen ions or 

 of the formation of any salts. The titration of a 

 sodium silicate solution indicated that this may 

 have been due to polymerization of the acid. 

 Although the first results would indicate that 

 sodium silicate is complete^ hydrolyzed in dilute 

 solution, titrations with phenolphthaleiu indicator 

 show tliis is not so. 



Synthesis of urea with the enzyme urease: Ed- 

 VCARD Mack and Donald S. Villars. The rever- 

 sible action of enzymes has been already shown 

 in several cases, but has never been demonstrated 

 for urease. In the present paper, it is proved 

 beyond any doubt that the equilibrium in the re- 

 action (NHo)2C0 + 2H2O ^ (NH4)'2C03 can 

 be approached from the (NH4)2C03 side, and 

 that the presence of urease hastens very decidedly 

 the attainment of equilibrium. Previous failure 

 to detect the effect was due to (1) starting with 

 too dilute a solution of (NH4)2C03 and (2) not 

 waiting a long enough time for the action, which 

 even in the presence of urease is slow. 



The action of urease in the decomposition of 

 urea: Edv?ard Mack and Donald S. Villars. 

 ■ From the work of E. A. Werner and others it 

 seems probable that urea in its reaction with 

 water to form ammonium oaAonate takes two 

 courses: (1) it forms ammonium .cynaaiate as an 

 intermediate product, which is itself changed to 

 ammonium carbonate; and (2) it forms ammo- 

 nium carbamate, whicli is hydrolyzed to car- 

 bonate. By a process of elimination, it has been 

 possible, in the present paper, to show that it is 

 the transformation of urea into ammonium car- 

 bamate which is catalyzed by the presence of the 



enzyme. Process (1) is not affected by urease. 

 It proceeds at its normal rate in the presence of 

 the enzyme. 

 ■ The acceleration of the hydrolysis of mustard 

 gas 61/ alkaline colloidal solutions : Egbert E. 

 Wilson and Everett W. Fuller. A careful 

 series of experiments was carried out to deter- 

 mine the mechanism by which alkaline colloidal 

 solutions, such as those of sulfonated corn oil, 

 so greatly accelerate the removal of mustard gas 

 from contaminated clothing. It was found that 

 these accelerating solutions do not increase the 

 solubility of the mustard gas in the aqueous 

 phase nor the specific rate of hydrolysis, but that 

 in solutions of proper alkalinity they act as car- • 

 riers of mustard gas. The acid produced by the 

 hydrolysis precipitates out tiny oil globules in 

 the aqueous film adjacent to the liquid mustard. 

 gas, and these globules rapidly dissolve unhydro- 

 lyzed mustard gas, and are then swept up into 

 the alkaline portion of the solution and redis- 

 solved, thus permitting rapid hydrolysis of the 

 mustard gas which they carry. Part of the ac- 

 celeration is also due to the fact that these col- 

 loidal solutions keep the mustard gas spread out 

 in a thin film on the cloth, instead of causing it 

 to draw up into globules, as happens in the pres- 

 ence of solutions of higher interfacial tension. 



Hydrogen ion concentration and photooUemical 

 reaction velocity: G. S. Forbes and J. C. Wood- 

 house. The speed of photochemical oxidation of 

 quinine by CrOs in unvaried concentration^ is 

 nearly constant from O.5NH2SO4 at least to 

 2.5NH2SO4. Below 0.5N, the order of reaction 

 ■vrith respect to hydrogen ion N^ increases. At 

 O.OIN (the lowest concentration practicable) it is 

 about 1 and is rapidly increasing, presumably 

 toward 2 " the value of N^ in the dark. 

 Previously N had been shown, as small con- 



■> cr 03 



centrations were reached, to increase from to 1, 

 its value in the dark. The conclusion follows 

 that the oxidation is a reaction stage separate 

 from a preceding stage of photochemical sensi- 

 tization, and slow with respect to it only at low 

 concentrations. Such relations are doubtless more 

 common than suspected. 



The inhibition of the ■photochemical decomposi- 

 tion of hydrogen peroxide solutions: Wm. T. 

 Anderson, Jr., and Hugh S. Taylor. (1) The 

 inliibitory effects of 25 typical organic com- 

 pounds on the photochemical decomposition of 

 hydrogen peroxide solutions have been studied in 

 four definite spectral regions of the ultra-violet; 

 (2) The inhibition by such agents has been asso- 



