184 



Mr. N. Campbell on the 



that the " absorption curve " for the solutions was not 

 accurately exponential and detailed investigations on this 

 point were made. 



In the first place, it was investigated whether, through 

 any defect in the apparatus, the absorption curve for a solid 

 deviated from the exponential form. Table I. gives the 

 results for measurements on sulphur, a solid which was 

 convenient for the purpose. The results are plotted in 

 diagram 4, and it will be seen that there is no evidence of 

 a departure from the theoretical straight line, (m is the 

 mass of the substances in the tray.) 



Table I.- 



-Sulphur. 



m. 



logio 1 - 



(J) 



4- -3874=:log 10 I 



•3304 



•2648 



•2387 



•1741 



•1255 



•0664 



•0327 

 -•0285 



•1324 



(2) 1-025 



(3) 2-244 



(4) 2-757 



(5) 4-109 



(6) 5-004 



(7) 6-120 



(8) 6-680 



(9) 7-755 



(10) 9-667 





Calculated value of X/p 6"967 ±0-038. 

 (Crowthcr gives 6*6.) 



Fie:. 4. 



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K^ 





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ZOG, ,„ I 



Other solids investigated were filter-paper, aluminium, and 

 the solutes of the solutions used. Observations of these salts^ 



