INDEX. 



353 



of, 100 ; radiation emissive power 

 of, 226 ; radiation reflective power 

 of, 230, 231 



Tobin system of ventilation, 61, 62 

 Tourmaline, radiating power of, 240 

 Trachyte, heat conductivity of, 103 

 Trade winds, 56 



Tradescantia discolor, osmosis in, 327 

 Translation, motion of, 133, 134 ; energy 



of, 134 ; velocity of, 134-135 

 Transparency, 234 



Transpiration or effusion. See Effusion. 

 Trap, heat conductivity of, 103 

 Travers, on liquefaction of gases, 197, 



199 



Triple point, 309 

 Tripler, liquefaction of gas, 198 

 Tyndall, on regelation, 201 ; on trans- 

 parency and opaqueness of iodine 

 in solution to radiation, 234 ; on 

 radiation and absorption by gases, 

 234-236 ; on radiation of platinum, 

 248 



UNIT of heat, 65 



VAN DER WAALS, gas equation of, 152, 

 193-195; on critical constants, 196, 

 197 



Van t'Hoff, on osmotic pressure, 324 et 

 seq.; application of thermodyna- 

 mics, 328-332 



Vapour, use of term, 158, 159; vapour- 

 liquid change of state, 157-200; 

 latent heat of, 178-182 



Vapour, density of gases, 175, 178 



Vapour-pressures, 172-175; of curved 

 surfaces, 314-317 ; influence of hy- 

 drostatic pressure on, 317-319 



Velocity of molecules, 133 et seq. 



Ventilation, 61-63; Tobin system, 61, 

 62 



Vincent, on specific gravity of ice, 72 



Violle, on specific heat of platinum, 81 ; 

 on solar radiation, 253-255 



Visible rays, temperature of, 12 



Volume expansion of solids, 28 



WATER, expansion of, by heat, 3, 37-40 ; 

 boiling-point of, as a fixed point in 

 thermometric scales, 4, 5, 12 ; maxi- 

 mum density temperature of, 37-40 ; 

 specific heat of, as the standard for 

 unit quantity of heat, 65, 76-82, 

 121-128 ; water equivalent for heat, 

 capacity for heat, 66, 121-128 ; latent 

 heat of, 73, 157, 200. 203, 205 ; heat 

 conductivity of, 89, 90, 96, 103-106 ; 

 convection in, 90 ; molecules of, 133 ; 

 physical state of, 157 ; distillation 

 of, 161-163; boiling of, 163-167; 

 spheroidal state of, 182-184 ; critical 

 temperature and pressure of, 192, 



195; freezing of, 200, 205-207; 

 supercooling of, 200-201 ; relative 

 volume of ice and, 201 ; supposed 

 plasticity of, 202 ; isothermals of, 

 207 ; in the atmosphere, 209-219 ; 

 radiation absorption of, 243 ; en- 

 tropy of, 271, 281; adiabatics of, 

 287 ; value of 7 for, 289 ; change 

 from water to vapour. 309-312; 

 osmosis of, 327 et seq. 



Water capacity for heat, 66 



Water equivalent for heat, 66 



Water-ice change of state, 307-312 ; 

 influence of hydrostatic pressure on, 

 317-319 



Water-steam change of state, 185-188, 

 306 et seq. 



Watertight joints, 17 



Water-vapour in its relation to thunder 

 clouds, and winds, 57 ; molecular 

 weight, 85 ; specific heat, 85 ; mole- 

 cular heat, 85 ; viscosity of, 146, 

 147 ; mean free path, 147-149 ; col- 

 lision frequency, 147 ; number of 

 molecules in 1 cc., 149; mass of 

 one molecule, 149 ; diameter of 

 molecule, 149 ; tension of, 158 et seq.; 

 condensation of, on nuclei, 168 ( t seq.; 

 pressure of, 172-175, 206, 211-215; 

 hygrometry, 209; relative humidity, 

 209; dew point, 209 et seq.; ab- 

 sorptive power for dark radiations, 

 236 ; isothermal for, 260-261 ; change 

 from water to, and from ice to, 309- 

 312 ; pressure of, in curved surface, 

 316-317 



Water-wheel, efficiency of, 271-272 



Watterston, on temperature of the sun, 

 255 



Wax, electricity of, 113 ; melting of, 200 



Weather, type of, in cyclones, 58-59 



Weather forecasting, 57-60 ; use of 

 charts in, 58 



Weber, H. F., on specific neat of carbon, 

 boron, and silicon, 81-82 ; heat con- 

 ductivity of mercury, 99 ; of water, 

 104 



Wells, on dew, 219, 233; on formation 

 of ice, 233-234 



Welter. See Gay-Lussac 



White-heat, temperature of, 12 



White lead, absorptive power of, 229 



Wiedemann, on specific heat of gases, 

 84 ; of air, 119, 294 



Wiedemann and Franz, experiments on 

 heat and electric conductivities, 100 



Wien, on radiation, 248, 249, 342 



Wilson, C. T. R., on condensation of 

 water-vapour in air and gas, 171, 

 172 ; on solar radiation, 255 



Wilson and Gray, on solar radiation, 

 255 



Winds, 56; land and sea breezes, trade 



