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VIII. 



A NEW METHOD OF PRODUCING TENSION IN LIQUIDS. 

 By J. T. JACKSON, M.A. 



[Read, June 16 ; Received for Publication, June 26 ; Published, September 30, 1903.] 



That liquids are capable of sustaining a considerable pull, tension, 

 or negative pressure without rupture can be proved in various 

 ways. The mercury may stick in the top of a barometer-tube and 

 stand at a height of 33 or 34 inches. A siphon will work under 

 the exhausted receiver of an air-pump. A column of water will 

 remain in the longer limb of a J tube, even when the only pressure 

 on the free surface in the shorter limb is the vapour-pressure of 

 the water itself, and is quite incapable of supporting the column. 

 A glass bulb completely filled with water may be gradually cooled ; 

 and the vapour-filled space left, as the water contracts, will make 

 its appearance, not gradually, but suddenly, and with a sharp 

 metallic click. 



To produce tension in liquids by any of these methods, the 

 liquid must have been boiled, and the glass with which it comes 

 in contact chemically cleaned. Very high tensions have been 

 obtained in these and other ways by Berthelot, 0. Reynolds, 

 Worthington, and others. 



It was shown by Joly and Dixon (Proc. Roy. Soc, 1894) that 

 the necessity for boiling the liquid arose, not because the presence 

 of dissolved air would render the liquid incapable of sustaining 

 tension, as had been previously assumed, but because the presence 

 of un wetted, or only partially wetted, dust-particles in suspension ' 

 would afford points of weakness at which rupture could readily 

 occur, and that the air expelled by boiling might be redissolved 

 without rendering the liquid incapable of sustaining tension. 



The question then arises as to whether this boiling' of the 

 liquid and chemical cleansing of the containing vessel is absolutely 

 necessary in order to render tension either possible or demonstrable. 

 Now it may be that evolution of gas from organic or other particles 



