426 OF CAPILLARY ATTRACTION AND THE COHESION OF FLUIDS. 



circumstanced, as neither to attract nor repel the fluid particles, and 

 consequently, the circumstances of the problem will not be at all 

 affected by supposing the tube to assume the form represented in the 

 diagram. 



Now, since the fluid in the tube A E is in equilibrio with that in the 

 tube CD, it is manifest, that the excess of pressure in AE, arising from 

 the superior height of the column, is destroyed by the vertical attrac- 

 tion of the tube, together with the mutual attraction of the fluid 

 particles in the tube AB ; in order therefore to analyze these different 

 attractions, we shall first consider those that take place under the 

 tube AB, in which the fluid rises above its natural level. 



534. In the first place then, it is evident, that the fluid in the 

 imaginary tube BE, is attracted, 



1. By the reciprocal action of its own particles, 



2. By the exterior fluid surrounding the tube BE, 



3. By the vertical attraction of the fluid in AB, and 



4. By the attraction of the glass in the tube AB. 



Now, the first and second of these attractions, are obviously 

 destroyed by the equal and similar attractions experienced by the 

 fluid in the opposite branch DC; consequently, their effects may be 

 entirely disregarded. But the vertical attraction of the fluid in the 

 tube AB, is also destroyed by an equal and opposite attraction 

 exerted by the fluid in BE, so that these balanced effects may likewise 

 be neglected, and there remains the attraction of the glass in AB, 

 which operates to destroy the excess of pressure exerted by the 

 elevated column BF. 



535. Again, the fluid in the lower portion of the cylindrical tube 

 AB, is attracted, 



1. By the reciprocal action of its own particles, 



2. By the fluid in the imaginary tube BE, 



3. By the attraction of the glass in the tube by which it is 



contained. 



But since the reciprocal attractions of the particles of a body, do 

 not communicate to it any motion if it is solid, we may, without 

 altering the circumstances of the problem, imagine the fluid in AB to 

 be frozen ; then, since the fluid in the lower part of AB, and that in the 

 imaginary tube BE, are acted on by equal and opposite attractions, these 

 attractions destroy each other, and consequently, their effects may be 

 neglected ; hence, the only effective force which remains to actuate 

 the fluid in AB, is the attraction of the glass containing it. Let this 



