250 SIXTH KKPORT — 1836. 



influence, it would be premature to reject the theory on that 

 ground, especially as the probability is that the effect which 

 this consideration has on the numerical results of the calculations 

 will at all events be small. In the paper just referred to I have 

 given I'easons for thinking that the law of molecular forces which 

 will account for the fluidity of liquids is also that for which the 

 effect of the superficial variation of density would be small in 

 capillary phsenomena. 



Subsequent to the experiments by M. Link, which are noticed 

 in the report on capillary attraction, others* were made by 

 the same author not agreeing in their results with the former. 

 After taking the precaution of freeing the solid plates against 

 which the fluid ascended from the effects of greasiness contracted 

 in polishing, it was not found as before, that different fluids 

 ascended to the same height between the same plates ; and the 

 experiments only partially confirmed the law to which theory 

 leads, of equal ascents of the same fluid between plates of differ- 

 ent material thoroughly moistened. The deviation from this 

 law is probably owing to the influence of particular affinities 

 between the solids and fluids which the theory cannot take into 

 account. 



More recently have appeared the results of experiments by 

 M. Frankenheim of Breslau, on the ascents of a great variety 

 of fluids in capillary glass tubesf. These were made for deter- 

 miningthecohesion,or as M. Frankenheim calls it, the synaphia 

 of fluid bodies. If h be the height of ascent, and r the radius 

 of the tube, the specific synaphia he considers to be proportional 



to \/ r ( h + -\. It is worthy of remark that the height of 



ascent of water in these experiments exceeds that of any of the 

 other fluids, and that the mixing of water with other fluids has 

 a very sensible effect in increasing their heights of ascent. It 

 also appears that an increase of temperature sensibly diminishes 

 the height of the ascending column. Similar experiments made 

 some years sincej by Mr. Emmett, assigned the highest ascent 

 (except in one instance) to water, and clearly showed also the 

 effect of an increase of temperature in diminishing the height. 

 Mr. Emmett has made the remark that to produce this diminu- 

 tion of height it is necessary merely to increase the temperature 

 of the upper surface of the fluid column. 



* Animlen tier Physik und Chemie, 1834, No. 38. 



+ Jnnalen der Pliy.s. und Chem., 1836, No. 2, p. 409. 



X Phil. May. and Annals, vol. i. 1827, p. 115 and 332. 



