t>16 Prof. Rankine and Mr. Smith on the Viscosities of 



Methane. 



The methane was generated by the action of water on 

 aluminium carbide. The gas was partially dried by passing- 

 it through a U-tube surrounded by a freezing mixture, and 

 then condensed in a second U-tube maintained at liquid air 

 temperature. When sufficient methane had been condensed, 

 a large quantity was allowed to evaporate in order to dis- 

 place the air and hydrogen from the U-tube. (Thehydro j,en 

 is a secondary product of the reaction.) Samples of methane 

 were then collected over mercury; since methane boils at 

 — 164° C. the gas was fairly dry, but to be quite sure of its 

 dryness and purity it was again condensed before intro- 

 duction into the viscometer. The permanent gases were 

 then pumped off at liquid air temperature ( — 183° C). At 

 this temperature methane exerts an appreciable vapour 

 pressure ; pumping was therefore continued until the pressure 

 indicated was constant. A sample of pure gas was then 

 introduced into the viscometer. 



Results : — 



Table I. — Methane. 



(Each time recorded is the mean of six observations, mutually 

 consistent to 0'4 per cent.) 



Time of fall in seconds. 

 Temperatnre 



Capillary 

 Correction 



Corrected 

 Time 



(deg. C). | 



! Whole pellet. Two segments. 



(a) 18-73 78-97 82-65 

 (c) 19-67 78-94: . \ 82-65 



(b) 998 9664 99-95 



0-0426 

 0-0429 



00320 



75-61 

 75 - 55 



93-55 



Making the small corrections to bring these results to the 

 tandard temperatures 17 o, 0C. and 100 o, C. we obtain 



^ 17 = 75*10 sees. 

 f 100 = 93'59 sees. 



Thei 



•efore (~) =1'246, whence Sutherland's Con- 



methane 



stantC = 198. 



Alsoatl7°-0C fmeth 



5*10 



= 0-6057. 



Correcting for slipping 



fair 123-98 



^^L =0-6052. 



