VISCOSITY. 19 



Noyes * observed a maximum conductivity with N/10 potassium and sodium 

 chlorides, in water, at 280. The formula of Slotte 2 for variation of fluidity 





holds at low temperatures, so that combining this formula with that of 

 Abegg and Seitz for decrease in dielectric constant, 



- - 

 ~ 



Bousfield and Lowry 3 give, as the complete formula representing the effect 

 of temperature on conductivity, 



Reference should also be made to the work of Hechler. 4 



VISCOSITY. 



The majority of workers have confined themselves either to viscosity 

 determinations alone, or to conductivity determinations alone. We must, 

 therefore, consider some of these if we wish to see clearly the relations be- 

 tween the phenomena. 



We need simply mention here the work of Poiseuille, 5 Noack, 6 Pagliani and 

 Battelli, 7 Slotte, 8 Gartenmeister, 9 and Traube. 10 The monumental work of 

 Thorpe and Rodger u merits more careful attention. They worked with very 

 great accuracy both with pure liquids and with mixtures, 12 and over a con- 

 siderable range of temperature. They have shown that the formula of Slotte 

 gives the best results. They proved, conclusively, what had been hinted at 

 before, that 



Viscosity may be taken as the sum of the attractive forces in play between the mo'.e- 

 cules ; . . . that an increment of CH 2 in chemical composition, or the substitution of an 

 atom of Cl, Br, or I for an atom of hydrogen, brings about a definite change in the 

 magnitude of the viscosity. It is, therefore, made evident that viscosity or intermolec- 

 ular attraction is, in reality, a property of the atoms of which the molecules are com- 

 posed. Isomers have nearly but not the same viscosity, yet the effect of CH-2 is the same 

 as in the normal compounds. The effects due to ring grouping, iso- and double-linkages, 

 and changes in the condition of the oxygen may be quantitatively allowed for. . . . 

 But water and the alcohols show no agreement with the calculated values. 



'Ztschr. phys. Chem., 46, 323 (1903). 7 Atti di R. Ac. delle Sc. d. Torino, 20, 



Journ.Amer.Chem.Soc., 26, 134(1903). 607 (1885). 



2 Beibl.. 16, 182 (1892). Loc. cit. 



3 Proc. Roy. Soc., 74, 280 (1904). Ztschr. phys. Chem., 6, 524 (1890). 



* Dissertation Minister (1904). 10 Ber. d. chem. Gesell., 19, 871 (1886). 



6 Mem. Inst. Paris, 9, 433 (1896). "Phil. Trans., 185A, 307 (1894). 



e Wied. Ann., 27, 289 (1886). n Journ. Chem. Soc., 51, 360 (1897). 



