OF ARTS AND SCIENCES. 57 



act results which might throw some light on the question raised 

 in that paper,* as to whether the 1st and 2d series there pre- 

 sented should he considered isomeric. For the same reason, it 

 seemed desirable also, before publication, that the relations of 

 these series should be further studied by at least a preliminary 

 examination of some of the more important chemical properties of 

 the different bodies which they comprise. With no immediate 

 prospect of being able to pursue these inquiries, — already so long 

 deferred from unavoidable causes, — it seems now advisable to 

 publish the results obtained, without relinquishing, however, the 

 hope of continuing the investigation. 



Notwithstanding the fact, as above intimated, that some of the 

 results to be presented are not entirely satisfactory, they are pub- 

 lished in the belief that they are more nearly correct than the cor- 

 responding results that others have obtained in the investigation of 

 this petroleum; and will, therefore, contribute materially to our 

 knowledge of the bodies obtained therefrom. This belief is justi- 

 fied by the circumstance that the different constituents of the 

 petroleum were separated by a process far more searching and re- 

 liable than any distillatory process that had been applied to such 

 a mixture ; f hence, that the several bodies examined were obtained 

 in a state approximating much nearer to purity than seems possible 

 by any other method of fractional distillation yet devised. As a 

 natural consequence, some of the more important results that I 

 have obtained in the study of this petroleum differ essentially 

 from those of other investigators of the same material, notably 

 those of Pelouze and Cahours, whose researches are often quoted as 

 authority on this subject. $ 



Before proceeding to give the experimental results which it is 

 the special object of this paper to furnish, it may be of service, 

 and may excite additional interest in the subject, to recall briefly 

 some of the facts furnished in my former paper, and to specify 

 some of the more striking differences between my results and those 

 of the chemists above mentioned. 



In the memoir first above referred to (pp. 166, 167), the hydro- 

 carbons that I have separated from this petroleum are classified 



* See foot-note, page 167. 



t " Process of Fractional Condensation," etc., Memoirs of the American 

 Academy, (N. S.) IX. 121. 



t Comptes Rendus, LIV. 1211, LVI. 505, LVII. 62. 



