268 M. Achille Cazin on Internal Work in Gases. 



is entirely independent of temperature, and of molecular struc- 

 ture, and cohesive strength, except so far as they affect the 

 quantity of the current, as is also shown by the magnetic cha- 

 racter of an electric current circulating through an electrolyte, 

 and also of the electric discharge in rarefied gases. 



XXXII. Memoir on Internal Work in Gases. 

 By M. Achille Cazin. 



[Concluded from p. 210.] 



Part II. — Application of theThermodynamical Formula 



TO THE INVESTIGATION OF THE INTERNAL WORK IN GASES. 



§ I. On the internal work performed in a gaseous mass when the 

 reservoir which contains it is connected with a second, empty 

 reservoir. 



AMONGST the problems which can be treated by means of 

 the thermodynamical formula?, and which relate to the ex- 

 periments described in the first part, the following is the most 

 simple : — 



Problem I. — In a reservoir whose sides are impermeable to 

 heat, there is 1 kilogramme of gas of which the volume and tem- 

 perature are v lf t k respectively ; this reservoir is connected with 

 a second, empty reservoir, with sides impermeable to heat, of v 2 

 capacity : to calculate the temperature t 1 and the pressure^' which 

 are established when the exchanges of heat and motion have en- 

 tirely ceased, and the internal work effected. 



Whilst the efflux is going on, heat disappears in the first 

 reservoir, with production of mechanical work; in the second 

 reservoir vires vivce are created which are equivalent to this work, 

 and which are finally transformed into heat. No external work 

 is either produced or spent ; no amount of heat is either taken 

 from or given to external bodies. If there were no attraction 

 between the molecules of the gas, no internal work would be 

 put in operation ; the heat created would be equal to the heat 

 which had disappeared, and finally the temperature would again 

 become t { . But if there is molecular attraction, it has at length 

 been overcome, and the quantity of heat which disappeared ex- 

 ceeds that which has been created ; the difference is equivalent 

 to the internal work produced, and the state of the gas is 



t'<t v v l —v Y \v 2i p'. 



The thermodynamical formulae enable us to calculate this final 

 state. 



