514 



And now the vapour tensions. Hackspill has found : 



/ = 264 316 331 340 350 360 365 762° C. 



7=537 589 604 613 623 633 638 1035° abs. 



;. = 0,1 0,75 1,15 1,35 1,75 2,13 2,3 760 mm. 



log\Op = -l 0,875 (-1) 0,061 0,130 0,243 0,328 0,362 2,881 



From the above found values of log^'ph we find in ram. log'^pk = 

 = 5,101 and 5,069, so that we have: 



/o^iO^= 6,101 5,226 5,040 4,971 4,858 4,773 4,739 2,220 

 P 



of =6,069 5,194 5,008 4,938 4,826 4,740 4,707 2,188 



— -1 = 2,296 2,005 1,932 1,887 1,841 1,796 1,774 I 0,7097 

 T 



of= 1,905 1,648 1,584 1,544 1,504 1,466 1,445 0,5067 



yielding /^io=2,66 2,61 2 61 2,63 2,64 2,66 2,67 3,13^4,52 

 of =3,19 3,15 3,16 3,20 3,21 3,23 3,26 4,32 -►4,34 



From the same considerations as for Na it follows also here again 

 very clearly that the upper series of values is better than the lower 

 one, and that therefore ^ = 1770=^ is preferable to 1560°. The 

 limiting values of ƒ for H are viz. /a = 87 = 10,40 to 10,00, or 

 yV =4,52 to 4,34. Probably the accurate value of Tje lies some- 

 what below 1770° abs. 



dt 

 Heycock gave 0,135 for — . When we assume /"' = 0,46 -. 397 = 



dp 



= 0,0016, the following formula follows for /V with ^^-=1770 



Ts = 1035 from the formula derived in § 3 : 



/io = y Lx 0,4343 + 0,710 X 0,00116 



•^' 1770 L^,135x760^ . ^ » 



= 606 X 0,4343 (0,00975 + 0,00082) — 263 X 0,0106 = 2,78. 



This value may be correct. It is larger than 2,67 and at the 

 same time smaller than 3,13 (tangent and chord, see for Na). 

 Perhaps Tk lies again somewhat below 1770° abs. 



5. Rubidium. 38°,5 + 273,1 = 311°,6 was found for the 

 absolute melting point temperature. This multiplied by 573 gives 

 7\. = 1662°. Ruff and Joh. (1905) found for the boiling-point 

 691°C. = 97r,l abs. This X 1,7 gives 1651. Let us take the round 

 value J 660 . On the other hand 311,6 X 4'/, = 1452, and 

 971,1 X 1,5 = 1457, averaged and rounded off 1450 . 



In consequence of this I J4 becomes =: 40,74 to 38,08, hence 



