556 



SCIENCE 



[N. S. Vol. LIV. No. 1405. 



small changes as certain as where the change 

 was more pronounced. 



Adsorption from solution: D. C. Lichtenwal- 

 KEB, A. L. Plenner and N. E. Gordon. Vary- 

 ing concentrated solutions of calcium sulphate, 

 calcium acid phosphate, magnesium sulphate, mag- 

 nesium acid phosphate, potassium sulphate, and 

 potassium acid phosphate were shaken with alu- 

 mina hydrogel and iron hydrogel and the maximum 

 adsorption determined by analyzing the solution 

 before and after shaking. The water of hydra- 

 tion was all figured as water of dilution. Both 

 gels show large adsorptions for each radical, and 

 especially was this true in the case of the phos- 

 phate radical. The adsorption increased with in- 

 crease of concentrate. The slow process of es- 

 tablishing equilibrium was also greatly marked. 



Effect of hydrogen-ion concentration on ad- 

 sorption : E. B. Starkey and N. E. Gordon. 

 Hydrated gels of iron and silica were prepared in 

 a very pure condition and shaken with a ISr/20 

 solution of KNO3, K,SO,, KHPOj. The hydrogen- 

 ion concentration had been varied by the intro- 

 duction of sodium hydroxide or hydrochloric acid 

 as the case might allow. The adsorption of each 

 ion was followed by analyzing the solution before 

 and after the shaking and figure the water of 

 hydration as water of dilution. It was found that 

 the adsorption of the metallic ion decreased with 

 an increase of hydrogen-ion concentration, while 

 the nitrate, sulphate, and phosphate radical varied 

 between no change of adsorption as in the case 

 of the nitrate radical to a very noticeable change 

 of adsorption in the case of the phosphate radical. 



The sorption of toluene and acetic acid and 

 fheir mixtures hy carton: A. M. Baker and J. W. 

 McBain. a general method is described for de- 

 termining the true sorption of both solvent and 

 solute in place of the merely relative values ob- 

 tained in the usual way for solutions. A maxi- 

 mum value for sorption is obtained which is in- 

 dependent of the absolute temperature; the ratio 

 between the saturation values is that of the mo- 

 lecular weights (acetic acid being present as 

 double molecules) ; and when solutions are em- 

 ployed, the total amount sorbed still corresponds 

 to a complete monomolecular film in which a cer- 

 tain number of double molecules of acetic acid 

 have replaced a corresponding number of mole- 

 cules of toluene. 



Drop weights of oils in solutions of emulsifying 

 agents: Eobert E. Wilson and Allen Abrams. 



The preparation and properties of ferric hy- 

 droxide gel: Egbert E. Wilson, William B. Boss 

 AND Leon W. Parsons. 



The measurem-ent of the plasticity of clays: 

 Robert E. Wilson and F. P. Hall. 



The transitional temperature of the sol and gel 

 forms in gelatin: Egbert Herman Bogue. Bing- 

 ham has shown that viscous liquids can be dis- 

 tinguished from plastic solids by a measurement 

 of the viscosity at varying pressures and an ex- 

 tending of the curves downward till they intersect 

 the axes. The former type intersect at the apex 

 of the viscosity-pressure axes, while the latter type 

 intersect upon the viscosity axis. By applying 

 the principle to gelatin solutions at different tem- 

 peratures and employing the MacMichael viscosim- 

 eter at varying speeds of rotation in place of the 

 capillary type at varying pressures, it is found 

 that the gelatine follows the law for a viscous 

 liquid at temperatures above 33 degrees C, while 

 at lower temperatures it follows the law for a 

 plastic solid. 



On the sivelling and gelation of gelatin: Egbert 

 Herman Bggue. Gelatine sols were treated with 

 solutions of the silicates of sodium in which the 

 Na^O: SiOz ratio varied regularly from 1:4 to 

 1: 1. The swelling, viscosity, alcohol number, and 

 Ph values were determined. The data indicate 

 that the effects resulting from such additions are 

 due in all cases to changes in the Ph rather than 

 to any other influence of the silicate. Gelation 

 appears to be dependent upon the tendency of 

 the substance to become solvated, the volume oc- 

 cupied by unit weight of dispersed phase being 

 the determined factor. When this volume is very 

 small or very large, the jelly consistency will be 

 low, and at intermediate values of volume per 

 unit weight the jelly consistency will reach its 

 maximum. 



Plasticity of colloids: Eugene C. Bingham. 



The fluidity-pressure curves of gelatine solu- 

 tions: S. E. Sheppard, Felix A. Elliott and 

 Harry D. Gideouse. Gelatine solutions were stud- 

 ied whose concentration varied from 1 per cent, 

 to 8 per cent, at temperatures of 25°, 28° and 

 30° C. The fluidities were measured with an 

 Ostwald type viscometer under pressures up to 

 900 mm. water. Ordinary, de-ashed and a mix- 

 ture of de-ashed and autoclaved de-ashed gelatines 

 were used. All measurable solutions showed little 

 evidence of plastic flow, the curves being linear 

 and approximately intersecting at a common point. 



