653 



ö,. According to Pellaton the critical temperature is J 44° C = 417°, 1 

 abs., so that 7,^ Q^ -. Tj, becomes = 7,^ X 271 = 40,2. Hence with 

 ]/a'}c = 5,6 we shall get about (from the critical data of Dewar 

 would namely follow 5,43, from those of Pellaton 5,75) 



l/Ak =b,Q X i/ 41,2 = 35,0 := 35. 

 Though this seems somewhat too high to us, as from 32 to 30 may 

 be expected, the order of magnitude is yet again in agreement with 

 what was found for it for [--^A with other elements. Possibly Q^ is 

 somewhat too high, or also l/a'i<^5,6; and perhaps in this case 

 — where ajc : a^ will be further from unity than for H^, N^ and 0^, 

 which have so much lower ci'itical temperatures — <9 will also be 

 so much smaller than 1, that the found value 35 will have to be 

 lowered to ± 32. 



With regard to Bromine Perman and Atkinson^) found t'ov Q^ the 

 value 57000 Gr.cal. With 7'a:=302°,2 C = 575,3 abs. we have 

 7,y(^, : Tk = 'i,^ V 99 = 14,7. We calculate with \/a\ = 7 : 



[/Ak = 7 X 1/15,7 = 27,7 = 28, 

 a value that is very plausible. 



In conclusion Iodine. Stark and Bodenstein (1910) found for it 

 Q, = 35500 Gr.cal., so that with r^; = 51 2° C = 785°, 1 abs. we 

 tind 7,, X 45,2 = 6,7 for ' i ,, Q, -. 1\. With V^a'k = 9 this gives : 

 accordingly : 



[/Ak = 9 X 1/7,7 = 25,0 = 25. 



Nor is this value, though somewhat small, at all impossible. 



6. Conclusion. 



It has, indeed, appeared very clearly from the above, that the 

 heats of dissociation Q,,, on the decomposition of the mole- 

 cules H,, N^, 0„ Clj, etc. into their atoms, are perfectly- 

 accounted for by the increased valence attractions \ A of 

 the separate atoms found by us in earlier papers. 



By means of (1) or (1") we are henceforth able to calculate Q^„ 

 when \''a and y/A are known or reversely to compute I .<4 accord ing 

 to (2), when Q^ is known. 



In Gibbs-Planck's well-known formula for the dissociation of gases*) 



1) Ibid. 33, 215 (1900). 



2) Of course this formula has nothing to do with the sn-called theorem of heat 

 of Nernst, as many pupils and followers of this srientist erroneously think (cf. 

 many articles in many periodics). The formula was already given in nuce by 

 GiBBS in 1878, and was later frequently elaborated by Planck (1887), v. d. Waals 

 (1891), myself (1892), Duhem (1893) and many others for different cases. [Cf. 



