December 22, 1922] 



SCIENCE 



727 



bustion wftth hydrogen and the N2 is obtained by 

 difference. In the absorption train oone. H0SO4 

 is uaed to absorb NO,, and part lof the NO if the 

 latter is present "ivith NO2. The total nitrogen 

 and the nitrous nitrogen in the acid are after- 

 ward determined, and from them the NO2 and NO 

 ajbsorbed are calculated. A definite volume of 

 sfcd. permanganate soln., acidified with H3PO4, 

 is used to absorb the rest of the NO, and after- 

 ward the excess permanganate is determined. The 

 total NO origiually present is the sum of that 

 absorbed in the H2SO4 and in the permanganate 

 soln. The method was tried on known quantities 

 of the gases, and was found satisfactory. 



The action of hydrogen peroxide on photo- 

 graphic gelatino-silver halide emulsions: 8. E. 

 Sheppabd and E. P. Wightman. A detailed 

 study of the action of hydrogen peroxide on pho- 

 tographic plates has been made with the idea of 

 obtaining more complete data on the subject in 

 order to compare the action with that of light in 

 the formation of latent images. Both the inten- 

 sity (concentration) and time factors were consid- 

 ered as well as development conditions. As a side 

 problem it was found necessary to consider also 

 the effect of concentration of the acid (or alkali) 

 content of the hydrogen peroxide. The effects are 

 in many ways quite similar to the action of light. 

 Other conclusions can not be drawn until further 

 work has been completed. We have proposed the 

 tentative hypothesis that silver nuclei in the silver- 

 haMde grains serve as catalytio agents for the 

 decomposition of hydrogen peroxide which is 

 ehemi- luminescent. 



Eeaotions at boundaries of phases; the problem 

 of promoter action and the theory of the latent 

 photographic image: Hugh S. Tatloe. From a 

 literature study and from investigations it has 

 been established that the boundaries of two 

 phases constitute a most reactive portion of a 

 heterogeneous system. Evidence is available to 

 show that a number of oases of promoter action 

 ean be attributed to enhanced reactivity of mixed 

 catalysts at interfaces between the components of 

 the catalyst mixture. The analogy between the 

 development of the latent photographic image 

 and the reduction of metallic oxides by various 

 reducing gases at low temperatures can be estab- 

 lished. Studies of the latter are very suggestive 

 as to the nec^sary extent of nuclei production 

 precedent to the production of a developed image 

 in .the individual grain of the photographic emul- 

 sion. 

 Syd/rogen ion catalysis in lactone formation: 



H. W. Close and Hugh S. Taylor. A study of 

 the catalytic conversion of hydroxy-acids to lac- 

 tones, using acids as catalysts, has been made. 

 The influence of variation of the catalyzing of 

 acid and of its concentration, of added neutral 

 salts and of their concentration, of temperature 

 and of the solvent, have been made the object of 

 investigation. It has been shown that it is prob- 

 ably the non-hydrated hydrogen ion which is the 

 active catalytic agent. The remarkable results 

 which this leads to, when ether is used as solvent, 

 have been outlined and experimentally verified. 



The hydrogen ion concentration of huffer solu- 

 tions at elevated temperatures: Robert E. Wil- 

 son. Despite its importance from a number of 

 aspects, there is practically no data in the litera- 

 ture as to the hydrogen ion content of the varioois 

 recognized "buffer" solutions at temperatures 

 above 40° Centigrade. Since the p^j of neutral 

 water and of ordinary solutions of alkalies drops 

 off markedly with increasing temperature, on ac- 

 count of the increased ionization constant of 

 water, it was especially desired to determine how 

 the alkaline buffer solutions behaved in this 

 respect. Measurements have been made on vari- 

 ous borate, phosphate and phthalate solutions and 

 indicate that the change in Pjj between 30° to 

 90° (calculated on the assumption that the p 

 of 0.1 N HCl is constant) is very small, compared 

 with that of ordinary alkaline solutions. This is, 

 of course, due to the fact that all owe their buffer 

 action to the ionization of acid salts of some 

 polyvalent acid. A phosphate buffer solution has 

 been prepared which is acid at 30° and alkaline 

 •3st 90°, although its Pjj remains constant. Most 

 indicators behave much like the buffer solutions, 

 and hence a given color may indicate acidity at 

 low temperatures and alkalinity at higher tem- 

 peratures. The paper presents the results in 

 graphical form. 



Trades of alpha particles in gases: E. W. Ryan 

 and W; D. Hakkins. 



The ferrocyanide test for sine: B. D. Mullinis 

 and A. L. Stallbaumer. Potassium ferrocyanide 

 precipitates a white zinc ferrocyanide which, 

 when treated with bromine water, turns a ehar- 

 aoteristic yellow color. No systematic work has 

 been done to determine the best conditions for 

 the test or to compare its sensitiveness with that 

 of the hydrogen sulfide teat. Such work has been 

 done by the authors and leads to the following 

 conclusions: (1) K4Fe(Cn)s test for zinc is ten 

 times as delicate as the H2S test. 0.1 mg. of 

 zdnc ion in 50 c.e. of solution ean be detected, 



