LIQUIDS AND ALLIED EXPERIMENTS. 



59 



and tube. Inasmuch as the forces are known, it may be worth while to 



test the method for measuring the viscosity of the liquid. Table 16 and 



those which follow contain the date, the corresponding value of Vq, and the 



other data needed to compute k by equation (5). M denotes the mass of 



the float, p g its density, p w the density of the liquid at the temperature given. 



Diameters of vessels are referred to under 2,"; //', h", k'" are the vertical 



heights of bubble, the water head for the diver when sunk, and the effective 



height of the water level within the diver, above its mouth. The head h" 



is liable to vary in the lapse of time. 



Table 16. — Air-air through water. Vessel A (double tube). J/= 12.011; p g = 2.A,S^; 

 (7=43.14; float, 2r = 2.Q5; tube, 2r = 3-3; vessel, 2/=4.4. 6'=i.8, ^" = 4.7, 

 h'"=7.o. 



Date. 



Sept. 17. 

 18. 

 19. 

 20. 

 21 . 



23- 

 24. 



25- 



26. 



27. 

 28. 

 30. 



1 . 



2. 

 3- 



4- 

 5- 



7- 



Oct. 



9- 

 10. 



1 1 . 



Barom- 



t 



II 







eter. 







" 





°C. 







76.24 



20.7 



65.49 



5-775 



] 76.06 



21 .0 



65.80 



5 



796 



75-8 5 



21 .0 



65.26 



5 



740 



76.03 



21 .6 



64.86 



5 



703 



76.90 



18.5 



63.65 



5 



650 ! 



76.81 



17.0 



61.38 



5 



474 



77.00 



17.0 



61.08 



5 



447 



76.72 



17 3 



60.60 



5 



400 



76.54 



'7 4 



60.34 



5 



375 



76.31 



17.4 



59.70 



5 



318 



77 04 



19.0 



59.50 



5 



274 



76.90 



17.2 



58.52 



5 



216 



i 7603 



'7-7 



57-4' 



5 



109 



76.58 



18.2 



57-05 



5 



069 : 



76.33 



20.2 



56.74 



5 



0:0 ! 



76. 10 



23.0 



58.20 



5 



095 



76.69 



20.4 



56.68 



5 



002 



75-68 



19.0 



54 30 



4 



813 



76.34 



.9.8 



53-43 



4 



724 



76.78 



21 .2 



52.87 



4 



654 i 



76.27 



22.7 



52.64 



4 



6n j 



76.72 



21 .6 



51.62 



4 



539 



Date. 



Oct. 12. 

 <4- 

 15- 

 16. 



'7- 

 18. 

 19. 

 21 . 

 22 . 

 23- 

 24- 

 25- 

 26. 

 28. 

 29. 

 30. 

 Nov. 1 . 

 2 . 

 4 



Barom- 

 eter. 



II 



76.40 



76.88 

 76.08 

 76.92 



76-44 



76.38 



75-97 

 77.29 

 77.08 , 

 76.05 I 



75-29 1 

 75.68 

 75-66! 

 76.20 j 

 76.58 I 

 75. So I 



75 9' j 

 75.62 , 



77-33 

 76.89 



76.82 ; 



°c. 



22.6 

 22 . 3 



22-4 



19 



20. 



22 



22 



2 I 



21 



22.3 



23-3 



20.2 

 20.0 

 20.0 

 20.O 

 19.8 

 I9.4 

 19.4 

 18.7 

 18.5 

 18.2 



21 



4- 



97 



4- 



43 



4- 



97 



4 



27 



4- 



39 



4- 



77 



4- 



36 



3- 



83 



3- 



69 



3- 



83 



3 



9i 



3 



36 



3 



39 



3 



94 



3 



42 



3 



61 



3 



42 



3 



22 



3 



. 10 



3 



43 



3 



Vo 



489 

 385 



336 

 242 

 170 



•59 

 107 

 992 

 946 

 921 

 922 



S77 

 831 

 745 

 706 

 662 

 595 

 578 

 479 

 471 

 414 



The present case of diffusion of air through water in the double-tube 

 apparatus is rather a disappointment in comparison with the long series of 

 results obtained above with the single-tube apparatus, inasmuch as the 

 diffusion after all allowances are made for differences of constants takes 

 place much faster than in the original experiment. Fig. 17, moreover, 

 apart from fluctuations due to variation of solution with temperature, 

 shows two different rates, the slower in September preceding a in figure and 

 the faster in October, following a, whereas no variation whatever had taken 

 place in the apparatus to our knowledge. It is very difficult to interpret 

 this, for it is hardly conceivable that any appreciable change of equivalent 

 importance should have occurred in the air of the room. 



The excessive rate of diffusion here observed occurs for the case where 

 the diffusion column is narrowed throughout, to a nearly constant diameter 

 as compared with the large diffusion column above the swimmer which 



