2 PROF. OSBORNE REYNOLDS ON THE 



The limit, of 32 feet or thereabouts, to the height to 

 which water can be raised by suction in the common pump, 

 and the sinking of the mercury in the barometer-tube 

 {leaving the Torricellian vacuum above) until the column is 

 at most only 31 inches (sufficient to balance the highest 

 pressure of the atmosphere) , are phenomena so well known 

 as to be almost household words with us. It is not, there- 

 fore, without some fear of encountering simple incredulity 

 that I venture to state 



T?ie Object of this Communication. 



In the first place my purpose is to show that certain 

 facts, already fully established, afford grounds for believing 

 that almost all liquids, and particularly mercury and water, 

 are capable of offering resistance to rupture commensurate 

 with the resistance offered by solid materials. In the 

 second place, I have to describe certain experimental 

 results which, as far as they go, completely verify these 

 conclusions and subvert the general ideas previously men- 

 tioned as to the limits to the height to which mercury can 

 be suspended in a tube, or water raised by suction. And, 

 in conclusion, I shall endeavour to explain the nature of 

 the circumstances which have resulted in the practical 

 limits to these phenomena. 



The Separation of Liquids is not caused by Rupture. 



Although the smalluess of the force generally requisite 

 to separate a mass of liquid into parts leads to the suppo- 

 sition that the parts of the liquid have but little coherence, 

 it may be seen on close examination that this supposition 

 is not altogether legitimate ; for such separation of a 

 liquid as we ordinarily observe takes place at the surface 

 of the liquid, is caused by an indentation or running-in o 

 the surface, and not by an internal rupture or simultaneous 



