Boiling-point as related to Chemical Composition. 185 

 that in melting-point it tends to be about half that of 7. The 

 general mean value of -, or the number of degrees correspond- 

 ing to CH 2 , is 19°*086 — a number nearly identical with that 

 which, since the publication of Kopp's celebrated memoir, has 

 been held in so much repute by chemists. It is, however, 

 hardly necessary to point oat that this estimate can no longer 

 be introduced in an ordinary linear equation; neither is it 

 actually the same with any of the numbers of which it repre- 

 sents the mean. 



The boiling-points of the infinite olefines are the only linear 

 series as regards chemical composition, being all integral mul- 

 tiples of a modulus 61*554. The probable error of a single 

 determination of the modulus is '20258; of nine determina- 

 tions, '06753. Nine of these olefines have been traced in the 

 preceding lists. 



An important criterion of stability under ebullition is found 

 in the value of the integral multiple just referred to ; the sta- 

 bility of a series evidently being in proportion to this multiple. 

 As we have seen (§ 16), the multiple is decidedly increased 

 under diminished pressure. 



The boiling-point of an infinite " odd " olefine is always 

 identical with, or higher than, that of an " even " one. The 

 same remark, with a corresponding inference as to stability, 

 applies to their entire series. 



The boiling-points as well as melting-points of six of the 

 infinite olefines are given in the following table. The mean 

 values of the moduli were employed in the calculation. 



Source Boiling- Melting- 



point, point. 



Fatty alcohols (even) 1 173'90 



Paraffins (odd) V 553'99 133'77 



» (even) J ^ 



Ketones (even) > 140*45 



Ketates (even, A) ... J 



„ (odd, A) ... 923-31 153-83 



Thus the infinite olefine boiling at 553*99 has, as shown by 

 melting-point, three isomeric modifications ; the infinite olefine 

 melting at 140*45 may have three isomeric modifications ; and 

 the infinite olefine boiling at 923*31 melts at 153*83. 



The value of four times the modulus of boiling-point is 

 246*23. There can therefore be only four infinite olefines 

 between 0° and —273° (" absolute zero"). On the other 

 hand, the modulus of melting-point is contained forty-one 

 times (274*22, or 273*72 within the limits of probable error) 



