Gaseous Ammonia, Phospliine, and Arsine. 611 



Also at 15° C., 



108-3 



arsine 



TT"^' 125-3 



= 0-864. 



Correcting for slipping this becomes 0*862, hence, for 

 arsine, 



77 15 = 0-862 x 1-799 x 10" 4 C.G.S. units 



= 1-552 xl0~ 4 C.G.S. units. 



Also 



7/ 100 = 1-552 x 1-287 xlO" 4 C.G.S. units, 

 = 1-997 xlO" 4 C.G.S. units. 



These values give for Sutherland's Constant 

 = 300. 



The following table summarizes the data obtained, and in 

 addition gives the viscosities at 0° C, derived by extra- 

 polation by means of Sutherland's equation : — 



Table V. 

 Summary of Results. 



Gas. 



Temperature (cleg. C). 



Sutherland's 

 Constant. 



150 



1000 



o-o 



Air 



1-799 



1-129 



1-552 



2191 



1-303 

 1-450 

 1-997 



1-724 



(0-943) 

 1073 

 1-470 



117 



(370) 

 290 

 300 



Ammonia 



Phosphine 



Arsine 





As already indicated, we have only obtained the viscosity 

 of ammonia at 100° C. In order to estimate Sutherland's 

 Constant the value of another temperature is necessary. 

 Unfortunately, the values of the viscosity at 0° C. obtained 

 by previous observers are not very consistent. Vogel * 

 obtained 0*926 x 10" 4 C.G.S. units, and Thomsen t 0960 

 x tO -4 C.G.S. units. We have taken the mean of these 



* Yog-el, Berlin Dissertation, 1914. 



t Thomsen, Ann. der Physik^ xxxvi. p. 825. 



