62 Scientific Proceedings, Royal Dublin Society. 



solution and in contact with wet wood, was stable while sustaining consider- 

 able stresses. 



In our experiments the tension developed as in Berthelot's by the con- 

 traction of the cooling liquid was measured by the deformation of the 

 containing vessel, which was consequently made sufficiently large, and with 

 walls of sufficient elastic yield, to render its collapse appreciable. The 

 change in volume due to the pressure of one atmosphere was determined ; and 

 so the tensions producing the observed change could be estimated. We found 

 that the adhesion to the glass and to the conducting tracts of plants and the 

 water's own cohesion must be greater than 7*5 atm. 



More recently the author^ showed that the water in a cell, distended by 

 osmotic pressure, could also sustain a considerable tension. 



Having had occasion recently to look up Berthelot's paper, I repeated his 

 experiment on water enclosed in thick capillary tubes ; and as some of my 

 results give a much higher minor limit for tensile strength of water than 

 his, I liave thought it of interest to record them here. The dimensions 

 of the tubes used were as follows : — 



No. Length. Bore. Thickness of Wall. 



I. 22 cm. 1-0 mm. 2-0 mm. 



II. 22 cm. 1-0 m. 2-0 mm. 



III. 19 cm. 1-0 mm. 3-0 mm. 



IV. 19 cm. 1-0 mm. 30 mm. 



v. 14-5 cm. 1-0 mm. 3-0 mm. 



VI. 15 cm. 1-0 mm. 3-0 mm. 



VII. 15-5 cm. 1-0 mm. 30mm. 



VIII. 17-5 cm. 1-0 mm. 3-0 mm. 



In each case the tubes were first cleaned with a solution of caustic potash, 

 which was afterwards removed by repeated rinsing with boiled, distilled 

 water. A piece of the wood of the yew [Taxus haccata) was then introduced, 

 and, after being filled with boiled water, the tube was kept submerged in 

 boiling water for an hour or so. Before sealing the drawn-out end, the 

 water was allowed to cool ; and a millimetre or more of the bore was cleared 

 of water by warming tlie point in a flame. When all was cool, the fine end 

 was sealed. 



In the table given below is a record of my experiments; for each 

 experiment the temperature U at which the tube is completely filled, and 

 the temperature ti at which rupture took place, are given in the fifth and 

 sixth columns respectively. 



^ Dixon, A Transpiration Model, Proc. Roy. Dublin Soc, vol. x., 1903, p. 114. 



