84 THE ROYAL SOCIETY OF CANADA 



.'. r=1.9 grains per inch. 

 The number of inches that must be taken before the pull is equal 



P _ P 

 top grams =— - -^ 



p 

 Waterston's Q thus equals — ' 



Further he applied the principle of virtual work to a column of 



4 

 water in a capillary tube and deduced the formula Q = ~^, where we 



pdh 

 should deduce the formula T= —— . His experiments gave practi- 

 cally the same value for Q as above. 



If we calculate a correct value of Q at 86°F. ( = 30°C.) from the 

 present accepted value of T, viz., 71 dynes per cm. we get Q = 90 

 instead of Waterston's 132.9, or working from Waterston's Q back to 

 C. G. S. units we get 45| dynes per cm. Hence he was about 30% 

 in error. 



It is curious to read that Waterston himself got Q = 88 for very 

 narrow tubes tV inch in diam., but he concludes that such narrow 

 tubes give abnormal results. 



Selecting Q as 132 he says a better value of the 20 inch pull 

 WQuld be 38.26 grams. Waterston then advances from pulls to 

 energies and says that "to denude 20 sq. inches of surface would 

 require 38.26 grains descending one inch; or to denude 1 sq» inch, 

 1.9131 grains descending one inch vertical. This being the weight of 

 .007577 cub. inch of water this volume of water raised through one 

 inch is equivalent to the work of denuding a superficial stratum of 

 one square inch, of overcoming the integral cohesion force on one 

 side — the outer side — of a superficial stratum of molecules; being 

 one sixth of the cohesion integral of all the molecules in the stratum." 



The cohesion integral of one layer of the cubic inch is therefore 

 .04546 cubic inches raised one inch. "On applying heat to water to 

 convert it into vapour we overcome the cohesion force of all the 

 molecules and the quantity of work which this is equivalent to, we 

 can readily compute from the data afforded by M. Regnault and 

 Mr. Joule, assuming that the latent heat of steam be the cohesion 

 integral of all the molecules while in the liquid state. Thus, having 

 the cohesion integral of one stratum of a cubic inch and the cohesion 

 stratum of all the strata in a cubic inch, we obtain the number of 

 strata in an inch and have the absolute volume of an aqueous mole- 

 cule." 



