﻿of the common Surface of two Liquids, 



Table XII. 

 Flat drops of Mercury in Air (-£ =6771 J. 



373 



No. 



Substance 3. 



2r. 



K. 



h. 



K-Jc. 



a.. 



a, c ale. = 



a 13 + a 3- 



1. 

 2. 

 3. 

 4. 

 5. 

 6. 

 7. 

 8. 



Water 



millims. 

 20 

 32 

 38-2 

 45-5 

 20 

 30-2 



34 



millims. 

 3-529 

 3117 

 3164 

 3125 

 2-891 

 2-944 

 2905 

 2-837 



milliras. 

 0-830 

 0-770 

 0-796 

 0-755 

 0-811 

 0-869 

 0-875 

 0-687 



millims. 

 2-699 

 2347 

 2-368 

 2-370 

 2-080 

 2075 

 2030 

 2150 



mgrms. 

 49-33 

 37-30 

 37-96 

 38 03 

 29-30 

 29-16 

 27-90 

 31-30 



mgrms. 

 50-83 



137-95 

 128-57 



Olive-oil 





" 



Oil of turpentine. 



The observed values of a agree with the values calculated from 

 a 3 and a 13 according to Table X. § 10, and thus confirm the 

 theory. 



It is to be observed, however, that all observations do not give 

 this result, and that in water which is placed on mercury, u is 

 often less, in oil of turpentine on mercury « is often found 

 to be greater, than the theory would lead us to expect. 



The reason of this deviation is chiefly to be sought in the ad- 

 sorption of moisture, which is condensed from the atmosphere 

 on the surface of the mercury as soon as the latter is formed. 

 Since, for the liquids examined by me which could be present in 

 the form of vapour in the atmosphere, 



a x > a 13 -f-a 3 , 



whilst the adsorption was going on I observed a change in the 

 form of the drop, K and K — k became smaller. 



This condensation of vapour also takes place, as I have already* 

 attempted to prove, on the surface of metallic solids and solid 

 bodies generally, and in other physical phenomena (as, for ex- 

 ample, in experiments on radiation) is an important source of error 

 under circumstances in which Magnus f has designated it by the 

 name of Vaporhasion. 



A layer of condensed air on the surface of the mercury may 

 have a similar influence to that of a thin layer of liquid. 



The decrease of the capillary constant is to be attributed to 

 this condensation on the surface, which I have myself observed 

 to take place on flat drops of mercury in vacuo, since even this 



* Pogg. Ann. vol. cviii. p. 326 (1859). 

 t Ibid. vol. exxx. p. 207 (1867). 

 Phil. Mag. S. 4. Vol. 41. No. 274. May 1871. 



2C 



