S82 



The inexplicably small ariiomil for Propane is not able to take 

 away the impression that for these satnrate hydrocarbons the volnine 

 increases reguhirly and equally whenever J atom of C and 2 atoms 

 of H enter the molecule, and when we consider the almost perfect 



rp 



equality of — for Pentane and Isopentane, we come to the con- 



Pk 

 elusion that at least in these cases a rearrangement of the atoms 

 is no influence of importance. U for the mean of the above values 

 (with the exclusion of 2,37) 2,76 is ciiosen, the volumes would be 

 as the calculated values of the preceding table indicate. It is seen 

 that except for Propane, the differences are small, and the question 

 suggests itself whether for this substance there is a cause of error 

 in the determination of the critical quantities, e.g. a certain degree 

 of impurity. 



If in what follows the volume of the carbon atom is represented 

 by 0, and the volume of the hydrogen atom by H, we have the 

 following two equations for the determination of these two quantities: 



C + 4 H =z 3,483 



-h 2 H = 2.76 ') 



723 

 or H = —^ — = (),36i5 and C = 2,037. 



Some other determinations which will be discussed presently, have 

 led me to consider C below 2 as possible. With C = l,9, retaining 

 Clf, = 3,483, II would be equal to 0.396. Then CH, woidd have 

 fallen to 2,691, so it has changed only little. But whether one 

 assumes H^ 0,3615 or 11 = 0,396, it appears that there is a great 

 difference with the \'olume of H or H.^ as it would follow from the 

 critical data of hydrogen. With 7\. = 32 and /;/, = 19,4 we find 



rn 



— 1=1,65. And if we should assume the formula H^ for the molecule 



as I also did at first, H ^ 0,825 would follow from this, a value 

 which is certainly not in harmony with the above calculated value. 

 And the difference is so great that I was already again on the verge 

 of concluding, as I had often supposed before, that it would be 

 impossible to get in this way to the knowledge of the size of the 



1) From methylethylelhylene(iso) which, the structure being disregarded, lias 



C5H10 = 5 (GHo) as formula, we find ^ = i3,69, which would lead to GH^ = 2,73S. 



Ph 

 But from ethylene, which has 2 (GH2) as formula, we should find a somewhat 

 too great value, viz. : 2 (GHo) = 5,7 or GH^ = 2,85. Is this substance somewhat 

 associating ? 



