PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 495 



It would be unintelligible to report this lecture at length without the 

 aid of the drawings, to which Dr. Stevens made constant reference. 



The Chairman. — We have now arrived at the foundation of this vast 

 subject. An immense field remains to be explored, and, after what we have 

 just heard, it is needless for me to say that I know of no one who better 

 understands this subject, in all its bearings, and is more capable of doing 

 it justice than Dr. Stevens. 



Mr. Grieves. — Mr. Chairman, at the last meeting, Prof. Everett stated 

 that naptha and benzine were the same. In this opinion I differ, and hope 

 to be able to show their different atomical constituents if time would allow 

 this evening. I know that to separate the constituents of petroleum is 

 very diflScult and requires great care, and that no two chemists will arrive 

 at precisely the same results. There are over fifty different processes for 

 refining the oils ; and as the oils differ in different localities, they should 

 also be treated with different chemicals. As time will not allow this even- 

 ing, I will not enter further on this subject, but reserve for another occa- 

 sion the reasons that lead me to form this opinion. I have noticed that 

 there has been discovered recently a substance called sedillon, and which 

 is said to be superior to coal gas for illuminating purposes, and that it is 

 taken from petroleum, but I have found it is nothing more than carbon and 

 carbonic oxyd. There- is great variation in petroleum hydrometically, as 

 well as in the particles composing it. In one specimen the hydrometer 

 will show a certain density, while in another a marked difference will be 

 observed. Respecting the inquiry made at the last meeting by Mr. Palmer 

 as to what is carbon spirits, I have since learned that an article known by 

 that name is sometimes sold here ; it is properly eupione, the specific 

 gravity of which is .014. A mixture of naphtha, alcohol, spirits of turpen- 

 tine, and sometimes benzine, goes by that name. It was first got up for 

 illuminating purposes, but was unsuccessful, as it ignites at 80 degrees. 

 That which is sold here as naphtha is a mixture of benzine, naphtha and 

 eupione ; it has a worse smell than the odor of the polecat. 



After some debate the subject of "Petroleum" was continued for the next 

 evening, to allow Mr. Grieves to enter more fully on the subject. 



The Chairman. — As the term naphtha has been used very much in this 

 discussion, it may be proper to state that naphtha is a product of distilla- 

 tion, not homogeneous; it is composed of many substances. I have seen 

 benzine and naphtha used for the same purpose. Petroleum is a mixture 

 of a series of hydro carbons, and as they have not yet been separated, 

 and our knowledge of their constituents is exceedingly limited, anything 

 relating to them will be of great interest. 



Adjourned to Thursday evening, April 22d. 



John W. Chambers, Secretary pro tern. 



