Chemistry and Physics. . 65 



SCIENTIFIC INTELLIGENCE 



I. Chemistky and Physics. 



1. On the Viscosity of Mixtures of Miscible Liquids. — It has 

 been pointed out by Thorpe and Rodger that the properties of 

 a mixture of liquids are rarely identical with those which the 

 mixture should possess on the assumption that the influence exer- 

 cised by each constituent is proportional to its amount ; possibly 

 because the effect of solution in some cases is to break down the 

 complex molecular aggregates of which certain liquids appear to 

 be composed, and in other cases because it leads to the formation 

 of aggregates of the same or of dissimilar molecules. Hence 

 these authors have continued their experiments on the relation of 

 the viscosity of a mixture of two chemically indifferent and mis- 

 cible liquids to the viscosity of its constituents ; with a view to 

 determine whether the viscosity is related to the number of 

 molecules per unit volume or per unit surface. The pairs of 

 liquids used were carbon tetrachloride and benzene, methyl iodide 

 and carbon disulphide, and ether and chloroform. The results 

 obtained afford additional evidence of the fact that the viscosity 

 of a mixture of miscible and chemically indifferent liquids is 

 rarely if ever, under all conditions, a linear function of the com- 

 position. A liquid in a mixture rarely preserves the particular 

 viscosity it possesses when unmixed. As a rule the viscosity of 

 the mixture appears to be uniformly lower than the mixture rule 

 would indicate, though no simple rule can yet be traced between 

 the viscosity of a mixture and that of its constituents. — J. Chem. 

 Soc, lxxi, 360, April, 1897. G. f. b. 



2. On the Specific Heats of the Gaseous Elements.— The known 

 facts with respect to the specific heats of the gaseous elements 

 have been summarized by Berthelot. He points out four dis- 

 tinct cases : (1) where the ratio of the two specific heats is 1*66 

 and the molecules are generally believed to bemonatomic; (2) 

 where the ratio is 1*41 and the molecules behave as if they were 

 diatomic and show no sign of dissociation into monatomic mole- 

 cules, although at high temperatures there are indications that 

 such dissociation is beginning to take place ; (3) where the ratio 

 is 1*30 (chlorine, bromine and iodine) and the diatomic molecules 

 dissociate more or less completely at high temperatures. The 

 ratio in these cases indicates that a considerable amount of 

 internal work is done when the temperature of the gas is raised 

 between ordinary limits; (4) where the ratio is 1*175 and the 

 molecule is tetratomic, but becomes diatomic at high temperatures. 

 The specific heats at constant volume in the four cases are 3*0, 

 4*8, 6*6 and 11*4, and the ratios of the three chief numbers are not 

 far removed from 1:2:4. There is therefore some ground for 

 supposing that the specific heats of elementary gases at constant 



Am. Jour. Sci.— Fourth Series, Yol. IY, No. 1.— July, 1897. 

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