WM. THOMSON ON CONVECTIVE EQUILIBRIUM^ ETC. 125 



experiment worth repeating. I think it highly probable 

 thatj by using intense cold and very great pressure, an 

 amalgam of hydrogen might be formed. 



As metals generally retain their specific gravities when 

 they meet to form alloys_, it may be inferred that the fore- 

 going experiments indicate the specific gravity of mercury 

 in the solid state. This value, from the average of the 

 thirty-six determinations of specific gravity above given, 

 is 15-19. 



XI. — On the Convective Equilibrium of Temperature in the 

 Atmosphere, By Prof. Wm. Thomson, M.A., LL.D., 

 F.R.S., &c. 



Read January 21st, 1862, 



The particles composing any fluid mass are subject to 

 various changing influences, in particular of pressure, 

 whenever they are moved from one situation to another. 

 In this way they experience changes of temperature 

 altogether independent of the effects produced by the ra- 

 diation or conduction of heat. When all the parts of a 

 fluid are freely interchanged and not sensibly influenced by 

 radiation and conduction, the temperature of the fluid is said 

 to be in a state of convective equilibrium. The equations of 

 convective equilibrium in the atmosphere are as follows, 

 n, T, and W denoting the pressure, temperature, and 

 mass per cubic foot of the air at the earth^s surface, and 

 p, tj and p the same qualities of the air at any height x : — 



(«'"- 



which is the known relation between temperature and 

 pressure ; 



^ For proof, see foot-note, p. 129, below. 



