508 



2410X1^,9.10-* 33500 ] 



ak > = 10-4 _ 462,5 .10-4 



^ 72,44 72,44 



2700X14,5.10-4 39150 l' 



or a/, > — = 10-4 = 546,3 .10-4 



-^ 71,67 71,67 I 



from which we find : 



]/ai. > 21,5 or > 23,4 . 1 0-"^ ( e. g. |/a^. = 21,7 a 23,6 .10-'^). 



For pi, immediately follows from (as 8: R = S y, 273,1 =2185) 



^'^ ~ 2185 X ^A- 



the value 2410 2410 



Pk = — = = 77 i atm. 



/ 2185 X 142.10 •'i 3,103 



2700 2700 



or pk = ~ = = 835 



^ 2185 X 148.10-5 3,234 



from which log^" pk = 2,890 to 2,922 follows, which we should want, 

 when a series of vapour pressures above the melting point were 

 known of Lithium. But of this exceptional element literally nothing 

 more is known than the melting point and the density at 15° C. 

 Not even the boiling point or the density at the melting point. 

 Still less the coefficient of expansion in solid and liquid state. 



3. Sodium. Here we tread on firmer ground. The melting point 

 lies at 97°,5C. = 370°,6 abs. The boiling point lies at 882°,9 C.= 

 = 1156° abs. according to Heycock and Lamplough (1912). (Ruff 

 and JoHANNSEN gave 877°, 5 C in 1905). Hence the critical temperature 

 lies in the neighbourhood of 370,6 X 5\/, = 1977, resp. 1156 xlJ = 

 = 1965, mean 1970 ° abs. ; or, as lowest limit, in that of 370,6 X -47, = 

 = 1729, resp. 7156x1,5=1734, mean 1730° abs. We carry out 

 the calculations again at these two temperatures. 



With \^ Tic = from 44,38 to 41,59, we find from our formula (see 

 for Lithium) 2 y = from 2,686 to 2,580, yielding 7 = 1,34 to 1,29. 

 For y: (1 + y) we find further 0,573 to 0,563, hence for y': (1 +7)^ 

 the values from 0,329 to 0,317, so that the factor X becomes from 

 0,910^ to 0,919, and rp from 73,67 to 74,38. 



ViCENTiNi and Omodei (1888) found 0,9287 (liquid) for the density 

 at the melting point 97°, 6, so that /)„ can be calculated from 



/ 370,7\ ^ 



0,9287 = D, M -0,573 X Yöf^) = 0,892 DA 



^f 370,7\ 



or =i>j 1—0,563 X ^ = 0.879 X>„ 



V 1730 ' 



yielding i>„ = 1,041 to 1.056. 



