INTERNAL COHESION OF LIQUIDS. 3 



separation over any considerable area. Thus when we see 

 a stream of liquid break up to drops, the di'ops separate 

 gradually by the contraction of the necks joining them, as 

 shown in fig. i, and not suddenly as in fig. 2. And the 

 ease with which portions of a liquid may be separated by 

 the forcing or di-awing in of the surface affords no ground 



Fig. I. Fie. z. 



for assuming that the liquid is without coherence, any 

 more than does the ease with which we may cut a piece of 

 string, cloth, or metal with sharp shears, or even tear some 

 of these bodies by beginning at an edge, prove that they 

 are without strength to resist great force when these are 

 applied uniformly so as to call forth the resistance of all 

 the parts of the body simultaneously. It is true that under 

 certain circumstances we observe the internal rupture 

 of liquid — whenever bubbles are formed, as when water 

 is boiled; but under these circumstances we have no 

 means of estimating the forces which cause the internal 

 rupture : they are molecular in their action ; and, for all 

 we know, they may be very considerable. Having thus 

 pointed out that the ease of separation of the parts of a 

 mass of liquid does not even imply a want of cohesion on 

 the part of the liquid, I shall now point out that we have 

 in common phenomena 



B 2 



