OF ARTS AND SCIENCES. 59 



the whole liquid portion of the petroleum is made up of one con- 

 tinuous series, having the general formula -€„H 2n + 2; and, more- 

 over, that the solid paraffines from this source belong also to this 

 series, of which at least there is much reason to doubt. 



Concerning a natural product of great importance in itself and 

 in its relations, results so discordant as above indicated should 

 have a careful and impartial examination with reference to the 

 different conditions under which they were respectively obtained, 

 with the view to determine which should be regarded as the more 

 accurate. Having this purpose in view, and with the conviction 

 that the work done does not so much need repetition as to be un- 

 derstood, and believing that the facts that I have to present are 

 sufficient to establish at least the probability of the correctness of 

 the conclusions I have reached, it will be necessary, in the follow- 

 ing consideration of the subject, to make such further comparison 

 of their results with my own as the pursuit of the object defined 

 seems to require. 



Examination of the Petroleum. 



Of the Material employed. — Commercial Products from the 



Petroleum. 



In the investigation of this petroleum I have not operated 

 directly on the crude oil, but upon certain distillates obtained 

 from this on a manufacturing scale. Special care was taken to 

 procure these from a reliable source, and to obtain such as had not 

 been subjected to any chemical treatment; and also such, taken 

 collectively, as would fairly represent the natural product so far as 

 to include in sufficient quantity all of its constituents. A brief 

 description of these crude distillates, indicating their comparative 

 value as sources of supply of the different constituents, may not be 

 void of interest, and may be of service to such, especially, as may 

 have occasion to repeat any portion of the work. This remark is 

 suggested by a statement of Schorlemmer * with respect to one of 

 the members of my 1st series, viz. that boiling at 61°.3, that it 

 was not present in the petroleum that he worked upon. After the 



vapors of the more volatile ones, at temperatures below their true boiling- 

 points, or within the range of the 1st and 2d series, their true or natural posi- 

 tion in the series not admitting of determination until, by the process of sepa- 

 ration, the bodies shall have attained a comparatively high degree of purity. 

 * Philosophical Transactions, 1872, Vol. CLXII. p. 116. 



