TABLES 



257 



BAROMETRIC CONSTANTS. 



VAPOR TENSION. 



The pressure, expressed in millimeters of mercury, exerted by water-vapor in a closed space. 



CAPILLARITY 



Is the same for all kinds of tubes which the liquid will wet. 



Is inversely proportional to the diameter of the tube. 



Becomes inappreciable in tubes of about 2 cm. (J inch) diameter. 



For parallel plates and concentric cylinders is about J that of tubes. 



Lessens with increase of temperature by about .002 (.2%) of its height for 

 each degree C. 



Water (pure) at 18 rises in a tube of 1 mm. diameter 29.3 mm. (conventionally 

 30 mm.). 



Mercury at 1 8° is depressed in a tube of 1 mm. diameter approximately 9.2 mm. 

 (conventionally 9 mm.). 



