172 



RESEARCHES ON THE VOLATILE HYDROCARBONS. 



inaccuracy in the determination of the boiling-points, when it is considered that great 

 care was taken to obtain a high degree of purity and accuracy, and when it is consid- 

 ered also that previous observers have made this discrepancy larger than mine. It 

 was on account of the Fact that so small a discrepancy would naturally raise a doubt 



as to the reliability of the determinations, and fo 



th 



Kopp 



* 



consid- 



ered this 



of alkaloids as agreeing tolerably well with his general law, that spe 



cial care was taken 



my part 



I 



am 



fident. th 



fore, that the boiling-point difference here will not be found to vary more than a frac- 

 tion from 17°. Of the absolute accuracy of the boiling-points themselves I do not 

 speak so confidently, since these depend so much on the accuracy of the thermometer 



these high temperatures ; but the 



of any errors which may have 



be likely to alter the relation, and the difference between 



same. This remark applies with equal 



remain about the 



from this source would not 



the boiling-points would stii 



force as to the reliability of the other boiling-points presented in this paper, especially 



of those of high temperatures. 



It remains now to consider the foregoing facts with reference to the other theories 

 mentioned. 



Of the Calculated Boiling-points of Hydrocarbons by Schroder's Theory. 



The subjoined tables exhibit the 

 hydrocarbons,! as calculated accord 



boiling-points of the above-mentioned 



Schroder's last theory, in comparison 



th 



the boiling-points actually found. By this theory, as already stated, each double atom 

 of carbon (C 2 ) contained in a body is supposed to influence the boiling-point by 30 3 , 

 and each double atom of hydrogen (H 2 ) to influence the same 



10°; from 



of th 



infl 



the number 70 







be deducted, in order to find 



boiling-point. 



1. Hydrocarbons from Penmylvania Petroleum. 



1st Skuies. 



Formula. 



c 8 



Oh 

 C 



Hio 



16 *M8 



Ciq EL 



18 xx 20 



Determined 

 Boiling-point. 



Calculated Boiling- 

 point by Schroder's 

 theory. 



Difference between 



Calculated and Deter 



mined Boiling-point. 



c 



o.o 



30.2 

 61.3 



90.4 

 119.5 



150.8 



(?) 



O 





 20 



40 



60 



80 



100 



10.2 

 21.3 

 30.4 

 39.5 

 50.8 



* Annalen der Chemie und Pharmacie, 1855, XCVI. 24. 



t To avoid useless repetition, the hvdrocarbons from . 



coal-oil will be omitted in this series of 



tables, they being considered identical with the corresponding bodies from petroleum. 



