of Water to each other. 295 



When this experiment was made with a cylindrical 

 glass of much larger diameter, the effects of the adhesion 

 of the pellicle of the water to the sides of the vessel 

 were much less sensible with regard to those parts of 

 the same which were situated near the axis. It was dif- 

 ficult to prevent the small bodies which floated on the 

 surface of the water from uniting, and when united they 

 often formed masses too heavy to continue to be sup- 

 ported; and, having broken the pellicle of the water, 

 they fell to the bottom of the vessel. 



If the particles of water adhere strongly to each other, 

 it appears to me to be a necessary consequence that a 

 kind of pellicle will be formed at the upper surface of 

 the liquid, and even at all its surfaces, whatever may be 

 in other respects the mobility of these particles, or rather 

 of the small liquid masses composed of a great number 

 of them, when they are remote from the surface and 

 possess their fluidity without impediment. 



When a small solid body, placed on the surface of 

 water, becomes wetted, it immediately descends beneath 

 the pellicle, which no longer opposes its resistance. 

 At this period the viscidity of the water begins to mani- 

 fest itself in a very different manner, but with infinitely 

 less effect than when it acts at the confines of the 

 liquid. But it is not yet time to inquire into this part 

 of our subject. 



With a view to render sensible the resistance which 

 the pellicle of the inferior surface of a stratum of water 

 opposes to a solid body which passes through that 

 stratum by falling freely downwards, I made the follow- 

 ing experiment. 



Experiment No. 6. Having filled a small wine-glass 

 to about half its height with very pure mercury, I 



