OP ARTS AND SCIENCES. 65 



the petroleum are less at variance with mine, I am induced to con- 

 sider that the spurious hody in question is more probably one of 

 the two lying between 120° (a point at which we agree very nearly 

 both as to boiling-point and vapor density) and 175°, the point at 

 which my 3d, or €„H 2 „ series, begins. It matters little which of 

 these it is, and we will therefore assume it to be the lower one of 

 the two, or their first above 120°, viz. that boiling at 136°-138°, 

 which they represent by the formula £ 9 H 20 . This formula, it may 

 be observed, is the same that I have given to a body boiling at 

 about 150°, finding none intermediate between this and 127°; the 

 latter, however, is not of the same series, being isomeric with the 

 body boiling at 120°, having the formula -G 8 H 18 . 



The question as to the existence in the petroleum of a body 

 whose boiling-point lies between the limits of temperature indi- 

 cated, viz. 127° and 150°, is seen to be of more importance when 

 it is considered, as above stated, that it involves the question as 

 to the constitution or correctness of the formula or formulae of the 

 higher member or members of the series; and especially so if it be 

 held that the -G„H 2n + 2 series in petroleum, instead of terminating 

 at 150°, as I maintain, is really so extensive as alleged by Pelouze 

 and Cahours, — they having already assigned to it seven bodies of 

 boiling-points above 118°, the highest of which boils at 260°; and 

 assumed, as already stated, that this series goes on uninterrupted 

 to, and includes, the solid paraffines. For if, as I maintain, the 

 petroleum does not contain the body in question, and if the 

 •€„H 2n + 2 series has the wide range which they assert, then it 

 must follow that the formulae assigned by them to these seven or 

 more bodies would each require the deduction of -€H 2 , and hence 

 that their determinations would become almost worthless, since so 

 great a discrepancy would indicate for the substances a degree of 

 impurity sufficient to destroy confidence in the results that they 

 obtained in the further study of these bodies. I have assumed, in 

 this consideration, that the lower members of the series have been 

 correctly determined, there being no disagreement between their 

 determination and my own of the formula — -€sH 18 — of the body 

 boiling at 119°. 5 (11G -118° by their determination), nor of the 

 formula? of the lower members of the series. 



Trusting that a comparative examination of the results pre- 

 sented in this paper, giving due consideration to the fact of the 

 greater efficiency of the process employed in my proximate analj r sis 

 of the petroleum, will leave no room for doubt on the questions 

 vol. xxvu. (n. s. xix.) 5 



