FLUIDS DEFYING GRAVITY. 



This is the well-known action of the siphon, 

 by which water actually runs uphill in getting 

 out of the beaker by the bend of the tube. 



There is another case of water running up- 

 hill in consequence of a special operation of 

 capillary attraction. If the tube B is placed 

 in water, so that the upper end projects above 

 the surface, it will be seen that the water level 

 inside it stands higher than outside. This is 

 in consequence of the combined action of 

 surface tension and the proximity of an en- 

 circling solid substance which can be wetted 

 by the liquid. The smaller the tube the higher 

 the water rises inside. 



Now the siphon D has to be started by 

 first inverting it and filling both legs, or by 

 putting it in position and then applying suc- 

 tion at the lower end of the outside leg. But 

 if the tube be fine enough a capillary tube, 

 because its bore is as fine as a hair (Latin, 

 capillus) and if the bend be not too high 

 above the level of the water, the liquid can 

 surmount the bend by capillary attraction, and 

 then as it goes down the outer leg, having the 

 weight of its own increasing column to help it, it 

 gains power of movement, and acts as an 

 ordinary siphon of very small bore and great 

 friction. 



A piece of cloth or wick may be regarded 

 as a collection of very fine capillary tubes, since 

 it contains a great many surfaces in close 



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