﻿a Problem in Viscosity. 1011 



III. Experimental Results. 



The results of the experiments on flat strips are shown in 

 fig. 4, where t {estimated from t' by (5)} is plotted against 

 Vrjv* 5 V varied from 0'122-(V320 c.g.s. units, v from 

 2-46-7-85 cm. per sec, p from 08-1-2. The straight line is 

 calculated from (3). 



It was pointed out in I. that the assumptions used in the 

 derivation of equation (5) could not be accurately true. 

 Owing to the cooling of the wax, as soon as it leaves the 

 liquid surface its viscosity is increasing, so that it is to be 

 expected that the effective viscosity will be somewhat larger 



Fi-. 4. 















i 





























0.03 



















































































































f 



f 







































f 



/ 



























t observed 





/ 













002 





























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/ 









































































A 















































































s 



X 





t calculated 







0-01 

















^ 



V / 



s 



































/; 







































/ 



f 







































s 



y 







































y 







































/ 



s 







































10 



20 



than that measured. The observed thickness of film should 

 therefore be thicker than that calculated on the basis of the 

 measured value, as is actually found. 



But the difference is comparatively small ; and when it is 

 remembered that (3) involves no empirical constant, but is 

 calculated from measured values only, no doubt will be felt 

 that the theory offered is completely confirmed. 



The coating on the edges of the strip was much thinner 

 than on the central portion ; it was therefore to be expected 

 that surface-tension effects would be prominent in fine wires. 

 Preliminary measurements on the thickness of the coating 

 on wires of diameter less than 0*02 mm. showed that the 

 coatings were much thinner than were demanded by the 

 theory which takes only gravitation into account (eqn. (7)). 



