RELATION OF 

SURFACE-TENSION TO TEMPERATURE It appears from the experiments of Brunner and of Wolf on the ascent of water in tubes that at the temperature I° centigrade T =75•2o (1-0.001870 (Brunner) ; =76•o8 (1—o•oo2t+0.0000041512), for a tube •02346 cm. diameter (Wolf) ; =77.34(1—o.00l8it), for a tube •03o98 cm. diameter (Wolf) . Lord Kelvin has applied the principles of Thermodynamics to determine the thermal effects of increasing or diminishing the area of the free surface of a liquid, and has shown that in order to keep the temperature constant while the area of the surface increases by unity, an amount of heat must be supplied 275 to the liquid which is dynamically equivalent to the product of the absolute temperature into the decrement of the surface-tension per degree of temperature . We may call this the latent heat of surf ace-extension . It appears from the experiments of C . Brunner and C . J . E . Wolf that at ordinary temperatures the latent heat of extension of the surface of water is dynamically equivalent to about half the mechanical work doi1e in producing the surface-extension .