﻿L 508 ] 



XLVII. On the Viscosity and Molecular Dimensions of Sul- 

 phur Dioxide. By C. J. Smith, B.Sc, A.R.C.S., D.I.C., 



Research Student, Imperial College of Science and Tech- 

 nology, London *. 



RECENT work on the viscous properties of compounds 

 which are ordinarily gaseous having been successful 

 in elucidating the molecular structure of these compounds, it 

 was thought that it would be interesting to apply similar 

 methods in the case of sulphur dioxide, especially as Lang- 

 muir f has already suggested a possible arrangement of the 

 atoms which constitute this particular molecule. This paper 

 describes the necessary viscosity measurements for sulphur 

 dioxide. Previously the data regarding the viscosity of 

 this gas were very scanty and did not extend over a sufficient 

 range of temperature to determine Sutherland's constant — a' 

 factor of almost as great an importance as that of the viscosity 

 itself in determining the mean collision area of a molecule. 



Apparatus and Method of Observation. 



The apparatus and method of observation which have been 

 used for the purpose of measuring the viscosity of sulphur 

 dioxide have recently been fully described %, 



Method of Experiment. 



The mercury pellet, which was used to drive the gas through 

 a capillary tube which forms part of a complete circuit con- 

 sisting of this tube and a fall tube in which the pellet moves 

 between specified marks, is the same as that which was used 

 by the author in his experiments on carbon oxysulphide § . 

 The time of fall for air proved to be 105*53 sees, at 18*0° C. 

 With this time of fall the corresponding time of fall for 

 sulphur dioxide has been compared, and, with appropriate 

 corrections, this gives the relative viscosity of air and sulphur 

 dioxide. From this relative value the absolute viscosity has 

 been obtained by assuming that the viscosity of air at 

 18°-0 0. is 1-8 14 x 10' 4 C.G.S. units. In addition, the varia- 

 tion of viscosity with temperature has been derived from 

 comparisons of the corrected times of fall at atmospheric and 

 steam temperatures. 



* Communicated by Prof. Rankine. 



t Langinuir, Journ. Amer. Chem. Soc. vol. xli. p. 868 (1919). 

 % A. O. Rankine and 0. .7. Smith, Phil. Mag. vol. xlii. p. 601 (1921) ; 

 and C. J. Smith, Proc. Phys. Soc. vol. xxxiv. p. 155, June 1922. 

 § C. J. Smith, Phil. Mag. vol. xliv. p. 289 (1922). 



