98 Inquiries into the Principles of Liquid Attraction. 
focal seat of attraction, and an apparently less degree of atmos- 
pheric pressure at the acute angles, contributes to elevate the surface ; 
and by inspecting Fig. 2, which represents a vessel of a different 
description, it will be seen how a less focal seat of attraction, and a 
greater degree of atmospheric pressure at the obtuse angles, contri- 
bute to depress the surface. 
Soap bubbles will rise in tubes of a sufficiently large bore, in the 
same manner as liquids rise, but to a much greater height; but the 
experiment requires some care in preventing the air from interposing, 
which will retard the operation. (See Fig. 14.) 
Dr. Ure makes the elastic force of the vapor of water, at the tem- 
perature of 55°, equal to the pressure of a column of water about 
six inches in height; and consequently this pressure will sustain in 
capillary tubes, columns of liquid proportioned to the diameters of 
