THE 

 LONDON, EDINBURGH and DUBLIN 



PlIILOSOPHIOAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



JANUARY 1858. 



I. On Capillaritij and its relation to Latent Heat. 



By J. J. Waterston, Esq. 



To the Editors of the Philosophical Magazine and Journal. 



GeNTLEMENj 



IN the following paper I offer an account of some expeiiments 

 on capillarity, and certain inductions from tliem, suggested 

 by tlie modern views of the dynamical or 7t;o?-/>;-value of molecular 

 force. The argument kept in view is, if the capillarity of a liquid 

 is the exhibition of part of the cohesive force of the superhcial 

 stratum of its molecules, numerical relations with the latent heat 

 of its vapour ought to be demonstrable if latent heat is the mea- 

 sure of liquid cohesion. 



§ 1. As a general rule, the glass tubes and plates were washed 

 first with sulphuric acid, then with nitric acid and with distilled 

 water immediately previous to each set of observations. This 

 was especially necessary when water was the liquid under obser- 

 vation, as it does not attach itself so readily to glass as the spirits 

 and cethers ; it is also apt to dry off the glass surface above the 

 line of capillary adhesion. In all cases care was taken to ascer- 

 tain that the surface of the glass was wet at this part. When by 

 holding the tubes or plates vertical and gently swaying them up 

 and down, the capillary column plays with a delicate indepen- 

 dent motion, the results can always be depended upon if the 

 gla'is surface has been perfectly cleaned with acid. When ob- 

 serving at temperatures higher than that of the atmosphere, this 

 test had to be constantly apjjlied, otherwise the column slowly 

 descended below the point of capillary equilibrium, and no cer- 

 tain results could be obtained. 



& 3 Tlie following mode of observation was employed with 

 two tuljcs, A and B. ^ The diameters were measured by a scale 



Phil. May. S. 4. Vol. 15. No. 97. Jan, 1858. B 



