the Viscosity and Temperature of G 



ases. 



85 



ments of which the following Table gives the results, advantage 

 has been taken of the four methods of checking the results of 

 one experiment by another, by reversing the direction of now 

 of the air through the tubes, and heating alternately, in each 

 case, first one and then the other trough. In the Table, 

 the first column gives the number of the experiment ; column 

 second the direction of flow of the air (which entered at the 

 tube whose number is first given, and passed out from the other) ; 

 columns three, four, and live give the pressures at A, B, and 

 D respectively ; columns six and seven show the temperatures, 

 in Centigrade degrees, of the baths around tubes I. and II. 



Tt 4 ~\ 



respectively ; column eight shows the values of the ratio ^ 2 



at different temperatures ; column nine the values of 



u e. 



of 



7) at the higher to rj at the lower temperature ; column ten 

 shows the values of the exponent x in the equation tj = t x . This 

 is the quantity which it was the object of the experiments to 

 obtain. 



No. 



Direc- 

 tion. 



Pi- 



Pr 



Pr 



Ti. 



Tn. 



E! 4 A 9 





X. 



R/Xi' 







millim. imillim. 



millim. 













1. 



I.-II. 



759-9 



525-2 



16-3 



170 



170 



0-912 







2. 



»> 



>> 



549-3 



171 



170 



475 





1-083 



0-799 



4. 



>> 



759-8 



525-6 



180 



151 



151 



: 916 







5. 



»j 



>> 



584-4 



18-9 



i> 



)> 



0-921 







6. 





765-7 



550-9 



18 6 



17-8 



17-8 



0-934 







7. 



IL-I. 



» 



490-7 



17-7 



17-5 



99-0 





1-212 



0-776 



8. 



>» 



17 



491-2 



17 6 



175 



99-5 





1-206 



0-755 



9. 







4900 



17-3 



17 5 



99-8 





1-215 



0-780 



11. 



>» 



755-2 



467-8 



20-4 



00 



1000 





1-272 



0-771 



12. 



>» 



»> 



468-4 



19-4 



»? 



M 





1-267 



0-757 



13. 



5> 



?> 



467-9 



196 



?> 







1271 



0-768 



14. 





>> 



4677 



193 



>> 



>> 





1-273 



0-773 



16. 



if 





544-2 



20-7 



00 



00 



: 927 







17. 



I.-II. 



7567 



525 3 



23-4 



?» 



,, 



0-928 







18. 



>> 



i> 



594-8 



215 







109-0 





1-277 



782 



19. 



>> 



761-4 



529- 1 



16 I 



1000 



1000 



: 933 







20. 



»» 



7620 



530-2 



167 



M 





0-937 







21. 



>> 



7631 



452-2 



185 



1000 



00 





1-259 



0-738 



Vi 



of this Table, the value of 



In the calculation of the ratio 



R 4 X 2 V2 



— ! used was the mean of that obtained from experiments 16 



and 17, after correcting for temperature. The agreement of 

 these two values within 0*1 per cent, is a test of the accuracy 

 of the method, as the two experiments were made on different 



