503 



D.= 



3,17 X 232,15 



735,9 



=: 8,16 . (calculated) 



402,5.10-5x22412 90,21 



This value agrees pretty well with the earlier density determina- 

 tions (1863), which gave 7,7 or 7,8 — but badly with the later 

 ones by Nilson (1882), who found 11,0, and those by v. Bolton 

 (1908), who even found 12,2. The value of 6yfc has, therefore, possibly 

 been assumed too high. 



This is also evident from the value of 7^ : Tir . For the melting 

 point Wartenberg (1910) found, namely, 1700 to 1755° C. (The 

 Thorium contained only 0,15 "/o ^O- If ^e assume 1727° C, i.e. 

 2000° abs., Tk -. Tt,- would become = 1,47, which seems again too 

 low. The same thing, therefore, as for Zircon. If instead of 402,5. 10^^ 

 we assume for h]c the value 375.1 0"^, which also holds for lead, 

 7\. becomes somewhat higher, and then a value in the neighbour- 

 hood of 9,5 follows for 1)^, hence still too low. 



Finally we find for pjc-. 



0,0322 X 1681 . 10-4 



Pk 



1620. 10-8 



^= 330 atm. 



12. Recapitulation. When we recapitulate what was found 

 here, in a table, we get the following survey. 



12. Conclusion. It follows most convincingly from all that 

 precedes that — in order to determine the elements of the carbon 

 group (and of the Titanium group) — the values of the molecular 

 attractions [/ok • 10—'^ must be taken veri/ high, ranging from 32 for 

 carbon to 40 for lead. These values are very much higher than the 

 residual atti actions for the compounds of these elements, which range 

 from 3 to 11, as we saw before. (See I to IV). This means, there- 

 fore, simply that we have to do here with free atoms which ex- 

 hibit a so much greater attraction than the bound atoms in the 

 molecule. 



