338 On the Spread of Liquids on Solid Bodies. 



yet another way from the observation of flat bubbles or drops 

 of one liquid 2 in another liquid 3 or 4, beneath or upon a 

 glass plate. 



From equation (4), 



"I2 = ai3 + «23COS0 3? (5d) 



a i2 = a i4 + a 2 4COS0 4 ; 

 or, by subtraction, 



«14 — «13 = «23COS0 3 — a 24 COS0 4 . 



Let the flat glass correspond to the solid . . 

 „ olive-oil „ „ liquid 



» water » » „ 



„ alcohol „ „ „ 



then according to my earlier observations*, 



a 23 = 2*096 mgr., a 2 4 = 0'226 mgr., 

 ^3=17°, 4 =87° 48', 



«i4-«i3=2-001 mgr. -O009 mgr.; 



or if the boundary of glass and water « 13 is called x, 



a 14 —^= 1*992 mgr. 



According to this investigation also, the surface-tension of the 

 level bounding surface of glass and alcohol is therefore greater 

 than that of glass and water. 



If water be taken as fluid 3, and the various liquids of ob- 

 servations Nos. 2, 10-14, & 16 of the former researches men- 

 tioned!, as fluid 2, then the surface-tension of the common 

 boundary of glass and the liquid concerned may be calculated 

 from equation (5d), except an additive constant « 13 , or x. 



Table IX. 



Bounding surface of glass 

 with 



Surface-tension with 

 glass. 



a, l2 —x. 



Bisulphide of carbon ... 



mgr. 

 4145 

 2-815 

 2001 

 1-992 

 0-931 

 

 -38-23 



Olive-oil 







Water 







The figures of the last columns in both Tables VIII. and IX. 



* Pogg. Ann. cxxxix. p. 27 (1870) ; and Phil. Mag. [IV.] vol. xli. 

 p. 263 (April 1871). t Ibid. 



