SECOND LAW OF THERMODYNAMICS 239 



in which W is expressed in joules and T in degrees centigrade; and 

 (j> is expressed in terms of joules per degree. Thus one joule per 

 degree is the degeneration involved in the conversion of one joule of 

 work into heat at 1° C. on the absolute scale, or the amount involved 

 in the conversion of 1,000 joules into heat at 1,000° C. on the absolute 

 scale. 



To convert an amount of work W into heat at temperature T 1 

 involves W/T 1 units of degeneration, to convert the same amount of 

 work into heat at temperature T 2 involves W/T 2 units of degeneration, 

 and therefore to transfer an amount of heat equal to W from tempera- 

 ture T 1 to temperature T 2 must involve an amount of degeneration 

 equal to the excess of W/T 2 over W/T x or an amount equal to 

 W(l/T 2 — 1/T 1 ), or H(l/T 2 — 1/T 1 ), where H is the amount of 

 heat transferred. 



The Second Law of Thermodynamics 



(a) The thermodynamic degeneration which accompanies a sweep- 

 ing or irreversible process can not be directly repaired, nor can it be 

 repaired by any means without compensation. 



This is an entirely general statement of the second law of thermo- 

 dynamics. The direct repair of the degeneration due to the sweeping 

 process means the undoing of the havoc wrought by the process by 

 allowing the sweep to perform itself backwards, an idea which is exactly 

 as absurd as the idea of allowing a burned house to unburn itself. 

 Following are several specialized statements of the second law of 

 thermodynamics. 



(&) Heat can not pass directly from a cold body to a hot body, nor 

 can heat be transferred from a cold body to a hot body by any means 

 without compensation. 



(c) Heat can not be converted directly into work, nor can heat 

 be converted into work by any means without compensation. 



The direct conversion of heat into work would be the simple reverse 

 of any of the ordinary sweeping processes which involve the degenera- 

 tion of work into heat, that is, the direct conversion of work into heat 

 would be to allow the sweeping process to perform itself backwards. 

 For example, work is degenerated into heat in the bearing of a rotating 

 shaft, and we all know that to reverse the motion of the shaft does not 

 cause the bearing to grow cold and the heat so lost to appear as work 

 helping to drive the shaft. That would be a rotary engine indeed ! 

 There is an important general theorem in thermodynamics to the effect 

 that if two sweeping processes A and B involve the same amount of 

 degeneration, and if either of the processes, say A, has been allowed to 

 perform its sweep, then by a lever arrangement, as it were, the process 



