18 



SCIENCE 



[N. S. Vol. LIV. No. 1383 



completed. A range of liquids from water up to 

 the high petroleums has been investigated. The 

 results have been examined in the light of exist- 

 ing theories. Qualitatively they appear in agree- 

 ment with the Gibbs relation, those substances be- 

 ing adsorbed that lower the interfacial tension. 

 Qualitatively they can not be represented at all 

 by the Preundlich equation. A theory is advanced 

 that solubility and the effects of the enormous 

 curved surfaces present in the capillary pores are 

 the determining factor. 



Summary of study of system ammonia-water: 

 W. A. Patrick and B. S. Neuhausen. (1) A 

 static method has been developed for measuring 

 the partial pressure of a component which is rela- 

 tively very small compared to the partial pressure 

 of the second component. (2) This method has 

 been used to determine the partial pressures of 

 water and ammonia of concentrated ammonia solu- 

 tions at 0° C, 20° C, and 40° C, at partial 

 pressures of ammonia varying from 1,000 to 4,000 

 mm. The partial pressures of the ammonia were 

 measured to within 4 to 2 millimeters; and those 

 of the water to 0.08 millimeter. (3) The solu- 

 bility of ammonia in water was determined at 0° 

 C, 20° C, and 40° C, at pressures from 750 to 

 3,600 mm. The densities of these solutions were 

 also determined. (4) A theory of the nature of 

 solution of gases in liquids first advanced by 

 Graham has been amplified, and solutions of va- 

 rious gases in liquids classified on the basis of some 

 of the physical and chemical properties of the 

 gas. (5) The formula 



V=K 



\Po ' n 



has been found to represent well the solubility 

 of ammonia in water at varied temperatures and 

 pressures. In this formula V is the volume occu- 

 pied by the liquefied gas dissolved per gram of 

 water; p is the vapor tension and 6 the surface 

 tension of the liquefied gas at the temperature 

 while p is the equilibrium gas pressure. The con- 

 stant fc for ammonia has the value 0.49 and 1/n 

 has the value 0.69. 



Heat of toetting of silica gelatine: W. A. Pat- 

 rick and E. C. Grimm. The amount of heat liber- 

 ated when silica gelatine is wetted by a number 

 of liquids has been accurately measured in an 

 adiabatic calorimeter. The results have been ex- 

 amined from the standpoint of the surface ener- 

 gies involved. On the assumption that silica gela- 

 tine presents a surface that is essentially water, 



all of the experimental results were capable of 

 being brought into agreement with the idea that 

 the heat of wetting is essentially a manifestation 

 of changes of surface energy. The heat of wetting 

 of water between 0° and 4° was found to be 

 positive and greater than that at 20°. 



Adsorption iy precipitates. IV: Acclimatiza- 

 tion: Harry B. Weiser. The amount of electro- 

 lyte required to coagulate a colloid is influenced 

 by the rate of addition. Since the quantity of 

 electrolyte that will cause complete coagulation 

 when the addition is rapid will not cause complete 

 coagulation when the addition is slow, the colloid 

 is said to become acclimatized and the phenom- 

 enon is called ' ' acclimatization. ' ' This term is 

 a misnomer. The dropwise addition of an electro- 

 lyte throughout a prolonged period is accompanied 

 by fractional precipitation of the colloid. The ex- 

 cess electrolyte required to precipitate a colloid 

 by the slow process is due to removal of precipi- 

 tating ions by adsorption of the neutral particles 

 during fractional precipitation. The factors which 

 determine the excess electrolyte required for a 

 given slow rate of addition are: (1) the extent 

 to which the colloid undergoes fractional precipi- 

 tation; (2) the adsorbing power of the precipi- 

 tated colloid; and (3) the adsorbability of the 

 precipitating ion. 



The oxidation and luminescence of phosphorus. 

 III. Tile catalytic action of vapors: Haert B. 

 Weiser and Allen Garrison. Phosphorus tri- 

 oxide is an intermediate product in the complete 

 oxidation of phosphorus. The luminescence of 

 phosphorus is due to the oxidation of this lower 

 oxide. Certain vapors inhibit the oxidation of 

 phosphorus and others accelerate the oxidation. 

 Such substances are designated as catalysts, but 

 they are not catalysts in the ordinary sense in 

 which this term is used. The vapors are condensed 

 or adsorbed on the charged or uncharged oxidation 

 products of phosphorus (If^Oe and P2O5). If the 

 vapors react with phosphorus trioxide they increase 

 the rate of oxidation. If they are inert, they 

 prevent further oxidation of phosphorus trioxide 

 and also form a cloud near the surface of the 

 phosphorus. This cloud approaches nearer and 

 nearer the surface as the oxidation becomes less 

 energetic and in certain cases may form a pro- 

 tecting film that stops the oxidation entirely. 



Critical solution temperatures as criteria of liquid 

 purity: D. C. Jones. (By title.) 



Charles L. Parsons, 



Secretary 



