September 1, 1916] 



SCIENCE 



323 



gallon rate gave excellent results. Continuous 

 process now being tried for clarification alone. 

 Eesults good. Aeration period at least four hours. 

 Complete nitrification never obtained by aeration 

 even after 25 days. Nevertheless, activated sludge 

 process alone offers relief to present overtaxed 

 plant. 



Some Results on the Treatment of Packing House 



Sewage by the Aeration Process in the Presence 



of Activated Sludge: Paul Budnick and G. L. 



Noble. 

 The Saving Effected by Using a Softened Water 



in Boilers : G. S. Cotter. 

 The Treatment of Industrial Wastes: Harrison 



P. Eddy. 

 Some Studies on Chemical Self Purification in the 



Ohio River: Earle B. Phelps and Harold W. 



Streeter. 

 Oxygen Demand Determination in the Field : P. W. 



Bruckmiller. 

 The Determination of Nitrates in Sewages by the 



Ortho-Toluidine Reagent: Earle B. Phelps and 



H. L. Shoub. 

 Studies on the Removal of Manganese from Water 



Supplies: H. P. Corson and Edward Bartow. 

 The Value of Softened Water to a Railroad: E. C 



Bard well. 

 Softened Water and Its Benefits in Laundry Work : 



John H. Etan. 

 Some Features of Swimming Tank Control: W. 



Lee Lewis. 



The American literature offers very little direct 

 data on the epidemiology of swimming pools, 

 though there is general expression to the effect 

 that such pools may spread gastro-intestinal, res- 

 piratory and even venereal diseases if improperly 

 controlled. The rotating or continuous filtration 

 system maintains a more sanitary pool than inter- 

 mittent filling. Both should be supplemented by 

 daily sterilization. Pool water of Lake Michigan 

 type, as shown mathematically and experimentally, 

 should not be rotated under the conditions more 

 than three months on account of decreasing alka- 

 linity and increasing hardness. 



DIVISION OP PHYSICAL AND INORGANIC CHEMISTRY 



Irving Langmuir, Chairman 

 James Kendall, Secretary 

 The Chromic-Chromous Potential at Mercury Elec- 

 trodes: George Shannon Forbes and H. N. 

 Eichter. (Lantern.) 



Pure violet CrCl 3 , partially reduced to CrCl; by 

 purified hydrogen at 400° in quartz, was dissolved 



with stirring in ice-cold, tenth normal hydrochloric 

 acid. The solution, filtered into the cell, was al- 

 lowed to stand over pure mercury. If all opera- 

 tions were conducted in hydrogen or carbon diox- 

 ide absolutely free from oxygen, the potential rose 

 throughout two days to a constant maximum, 

 otherwise it fluctuated irregularly. Concentra- 

 tions at equilibrium were determined analytically. 

 Eeferred to normal hydrogen electrode as zero, 

 with correction for junction potentials, 



tt = — 0.400 + 0.065 log Criii/Crn. 



On platinum potentials reached a maximum about 

 0.16 volt lower, with evolution of hydrogen. 



Heterogeneous Equilibria between Aqueous and 

 Metallic Solutions: A Study of Mixed Sodium 

 and Potassium Salt Solutions at Total Concen- 

 trations varying from 0.2 N to 4.0 N: G. Mc- 

 Phail Smith and T. E. Ball. (Lantern.) 

 The Contamination of Precipitates in Gravimetric 

 Analysis: Solid Solution and Adsorption vs. 

 Higher-Order Compounds: G. McPhail Smith. 

 An Electrically Controlled Calorimeter for Meas- 

 uring Heats of Dilution: D. A. MacInnes and 

 J. M. Braham. (Lantern.) 

 On the Evolution of the Elements according to the 

 Hydrogen-Helium System: W. D. Harkins. 

 (Lantern.) 

 Theoretical Relations of the Atomic Weights: W. 



D. Harkins. (Lantern.) 

 A New Gravimetric Method of Determining Alum- 

 inum, and of Separating that Metal from Zinc, 

 Manganese, Nickel, Cobalt, Iron and Chromium: 

 Louis Kahlenberg and K. P. Young. 

 When ammonium salicylate is added to a dilute 

 solution of an aluminum salt, and this solution is 

 then boiled, there separates out in granular form 

 a basic aluminum salicylate of the composition 

 (A1(C,H 1 .0H.C06),)»-A1(0H),. This may be 

 readily filtered off, washed with hot water, ignited 

 and weighed as A1,0 3 . The precipitate is much 

 more readily handled than the usual slimy and 

 gelatinous precipitate of aluminum hydroxide. 

 Zinc, manganese, nickel, cobalt, ferrous iron and 

 chromium are not thus precipitated by ammonium 

 salicylate, which fact is the basis for the direct 

 and simple separation of these metals from alumi- 

 num. The solution should be fairly dilute, lest the 

 basic aluminum salicylate occlude notable amounts 

 of the other metals. If this should occur, redis- 

 solving the precipitate and then reprecipitating 

 from the dilute solution will secure a good sepa- 

 ration. Sodium salicylate may be used as the 



