December 2, 1921] 



SCIENCE 



555 



THE AMERICAN CHEMICAL SOCIETY. 



(Continued) 



DIVISION OF PHYSICAL AND INORGANIC CHEMISTRY 



H. N. Holmes, chairman. 

 S. E. Sheppard, secretary. 



Adsorption iy precipitates V.: Adsorption dur- 

 ing the precipitation of colloids by mixtures of 

 electrolytes: Harry B. Weiser. The precipitating 

 action of mixtures of two electrolytes is approxi- 

 mately additive if the precipitation value of each 

 is of the same order of magnitude such as fre- 

 quently obtains when the precipitating ions have 

 the same valence. The precipitating action of mix- 

 tures of electrolytes with widely varying precipita- 

 ting power may be far from additive but under 

 certain, conditions may approach an additive rela- 

 tionship. The determining influences are (1) the 

 effect of the presence of each precipitating ion on 

 the adsorption of the other and (2) the magni- 

 tude of the stabilizing action of the ion having 

 the same charge as the colloid. 



The influence of the concentration of colloids 

 on their precipitation 'by electrolytes: Harry B. 

 Weiser and Henry O. Nicholas. Burton and 

 Bishop {Jour. Phys. Chem., 24, 710 (1920)) 

 state that the precipitating action of univalent 

 ions increases and of trivalent ions decreases with 

 decreasing concentration of colloid while that of 

 divalent ions is almost independent of the colloid 

 concentration. By an extended series of experi- 

 ments with four different colloids this rule was 

 shown to be far from general. With three of the 

 colloids the precipitation value of all electrolytes 

 decreased as the concentration of the colloid de- 

 creased, the effect being least marked with electro- 

 lytes having univalent precipitating ions. The de- 

 termining factors are (1) the change in the 

 amount of adsorption necessary for neutraliza- 

 tion, (2) the change in the opportunity for col- 

 lision of the particles, (3) the influence of the 

 stabilizing ion particularly in the ease of electro- 

 lytes that precipitate in high concentration. 



Intermittent phosphorescence: Harry B. 

 Weiser. The luminescence of phosphorus is due 

 to the rapid oxidation of phosphorus trioxide to 

 phosphorus pentoxide. The luminescence is con- 

 tinuous only when the trioxide vapors are formed 

 as rapidly as the luminescent reaction proceeds; 

 the luminescence takes place in intermittent ex- 

 plosion waves when the velocity of formation of 

 trioxide is less than the velocity of the explosion 



wave. The pulsations may be very rapid or may 

 occur at intervals of several hours. The number 

 of luminescent waves in unit time is determined 

 by (1) the temperature, (2) the partial pressure 

 of oxygen, (3) the extent to which the heat of 

 reaction is absorbed by the containing vessel, (4) 

 the presence of "catalytic" vapors. 



The ternary system: silver perchlorate-benzene- 

 water: Arthur E. Hill. Silver perchlorate is 

 very soluble in water, and moderately soluble in 

 benzene. The system has been studied from the 

 temperature of the ternary entectic ( — ^58°) up 

 to the boiling points of the pure liquids. There 

 occur four quintuple points, and twelve equi- 

 libria. Of most interest is the equilibrium in 

 which three liquid phases are present, which may 

 exist from —2.2° C. to + 22.3° C. It appears 

 to be the only three-component system showing 

 three liquid layers derived from components in 

 which only one pair (water and benzene) show 

 the formation of two liquid phases. 



Bydrated oxalic acid as an analytical stand- 

 dard: Arthur E. Hill and Thomas M. Smith. 

 The common drawbacks to the use of hydrated 

 oxalic acid as a standard for oxidimetry and 

 alkalimetry are its retention of included water 

 and its irregularity in combined water due to 

 its distinct vapor tension. These two sources of 

 error should be eliminated by fine grinding, to 

 offer an escape for included water, and by dry- 

 ing to constant weight in an atmosp;here in| 

 which the aqueous tension is exactly that of 

 the hydrate. We have found that grinding to 

 pass a 100-mesh sieve meets the first requirement. 

 To meet the second, we have dried the com- 

 pounds over a mixture ef hydrated and dehy- 

 drated oxalic acid, which is the only drying agent 

 which can be in equilibrium with the compound 

 at all temperatures. The compound can be 

 brought to a constant composition within about 

 three hours, and agrees in its reducing action 

 upon KMnO, with Bureau of Standards sodium 

 oxalate within 0.03 per cent. 



Effect of the history of adsorbent on adsorp- 

 tion: E. C. Wiley and N. E. Gordon. Silica 

 gel was prepared containing various amounts of 

 water of hydration, and shaken with varying con- 

 centrations of different salt solutions. It was 

 found that the amount of hydration had some 

 effect on the adsorption of some salts. In most 

 instances the change was very small, but in 

 these cases the analytical method used made the 



