2 PROCEEDINGS OF THE AMERICAN ACADEMY. 



rions of the contiuent. A similar interest attaches to the Cana- 

 dian petroleum from the Coruiferous limestone, which has yielded 

 since 18G2 enormous quantities of oil within the limited areas, less 

 than thirty square miles, at Petrolia and Oil Springs. From the in- 

 formation already acquired concerning the nature of the sulphur petro- 

 leums, they seem to possess, beside their distinctive characteristics due 

 to sulphur constituents, qualities of other petroleums which differ 

 essentially in their composition. 



In the earlier attempts to ascertain the constituents of petroleum, 

 the methods then employed for fractional distillation were so inade- 

 quate that very little was accomplished. In 1862 the first systematic 

 examination of American petroleum was undertaken by Pelouze and 

 Cahours, * who showed the presence of the series of hydrocarbons 

 C„H2„_i_2? beginning with butane. On account of a want of suitable 

 apparatus for fractional distillation, their results lacked precision, and 

 the questionable assumption was based upon them that jDetroleura is 

 composed principally, including the heavier oils and paraffine, of the 

 homologues of marsh gas. In accordance with the suggestion of 

 Watts, these bodies were called the paraffine hydrocarbons, and as 

 such they have since been known in chemical literature. Having 

 obtained from coal oil a series of hydrocarbons corresponding to cer- 

 tain members of the series discovered by Pelouze and Cahours, Schor- 

 lemmer f submitted the more volatile portions of American petroleum 

 to distillation, and succeeded in separating hydrocarbons that had not 

 been recognized by Pelouze and Cahours. In a more thorough and 

 carefully conducted examination of Pennsylvania petroleum, carried on 

 contemporaneously with the investigations of the chemists mentioned 

 above, by means of an efficient fractional condenser devised especially 

 for this and other similar investigations, C. M. Warren t avoided the 

 errors of other experimenters and established beyond question the 

 presence in Pennsylvania oil of two series of hydrocarbons, each with 

 an homologous difference in boiling points for CHo of 30°, and each 

 member of one series differing in boiling point from the isomeric 

 member of the other series by a little less than 8°. One of the series 

 C„H2„ + 2 identified by Warrren terminates at 127°. 6, the other at 

 150°, the fractions of higher boiling points containing members of the 

 series C„H2„. The assumption of Pelouze and Cahours that the frac- 



* Comptes Rendus, LIV. 1241, LVI. 505, LVII. 62. 



t Journ. Chem. Soc, 1862, p. 419. 



{ Mem. Amer. Acad. (N. S.), IX. 135; Proc. Amer. Acad., XXVII. 56. 



