Peckhain.] A(\9 [Septcmbei- IS, 1868. 



correct and successful stud}" of the dense liquid and the solid 

 forms of bitumen. Ultimate analysis fails to throw any light 

 upon the true character of a solid bitumen. It may detect 

 traces of nitrogen, sulphur or oxygen, but fails to show whether 

 they are essential or accidental elements — whether they belong 

 to asphaltum or whether they are derived from organic impuri- 

 ties, with which every surface asphalt is contaminated. Methods 

 of anal3^sis I'equiring a high temperature are especially unsatis- 

 factory, because it is impossible to discriminate in the results 

 obtained between products of decomposition and those of com- 

 position. By perfecting and extending the application of this 

 process to a large number of liquid bitumens of known constitu- 

 tion, and studying the results of their decomposition, both solid 

 and gaseous, a method which in relation to asphaltum may in 

 one sense be termed synthetic, the answer to this most interest- 

 ing question of the origin of bitumens, may in some degree at 

 least be removed from the domain of pure speculation to that 

 of positive knowledge. 



More extended research ma}' lead to a modification of the 

 views herein expressed. It appears to me not unlikely that 

 petroleums exist intermediate between the classes A and />', 

 which contain proximate principles found in each of them, and 

 which, while they contain the paraffine series, may be susceptible 

 of experiencing the asphaltic change. It may also appear prob- 

 able that the more stable class A are entirely of vegetable 

 origin, Avhile the class />' is of animal origin ; a third and inter- 

 mediate class, should it be found to exist, being derived in part 

 from both sources. It is mj' intention to continue this reseach, 

 not onl}^ in order to obtain more exact results respecting those 

 oils already examined, but to extend its application to other 

 petroleuiTis. My object at present will be accomiDlished, if I 

 call the attention of those engaged in the study of petroleums, 

 to the consideration of these questions, the importance of which 

 to science and technology, circumstances have strongl}' im- 

 pressed upon my own mind. 



PiiOYiDENCE, R. I., Jul!/ 28t7i, 18G8. 



