22 
MM. Frankenheim, Sondhaus and Brunner have shewn the 
phenomena of capillary attraction to be functions of the tempera- 
ture and not of the density of liquids. 
The author stated that he had employed no new principle in 
his method of solution of the problem of the forms of the capil- 
lary surfaces, but had employed in a different manner the recog- 
nized properties of fluids, and treating each case as a distinct 
hydrostatical problem, solutions were obtained in the first 
instance for the cases of vertical parallel plates near together, 
and tubes of small diameter, with their lower ends immersed 
in liquid, by the statical property of forces acting on bodies, 
that the vertical and horizontal forces must balance each sepa- 
rately amongst themselves; and that a fluid by Pascal’s prin- 
ciple may be considered as separated into distinct portions by 
imaginary rigid films without the state of the fluid being altered. 
The vertical force exerted along the line of contact of the solid 
and liquid is shewn by Laplace to be the force which supports 
the weight of the liquid in capillary elevations above the level 
of the outside fluid, and the same must be the case when the 
liquid is separated by imaginary rigid films into portions like- 
wise. ‘This vertical force is balanced by the vertical component 
of the tension in the capillary surface of the liquid at the line 
of contact. The tension which may exist in the surface is 
limited by the attraction of aggregation from which it must be 
distinguished, as it is a force transmitted from the impressed 
force at the line of contact, and as in flexible solids, such as cords 
‘and sheets, it may vary from nothing to the utmost the attrac- 
tion of aggregation permits. The horizontal forces are only the 
horizontal components of the tension, which must therefore 
balance amongst themselves as in the catenary curve. For the 
capillary depression the procedure is the converse of that for 
capillary elevations. . 
With these considerations it was found that between vertical 
parallel plates for a first approximation the form of the perpen- 
