408 



in the hydrogen, though trifling in amount, being upon the 

 opposite side to that on which it usually occurs, it became 

 expedient to resort to some method of verification. The 

 specific gravity of the vapour of the oil was therefore taken 

 by the well known method of Dumas, and found to be 3.137 : 

 the formula C5 h^ o would make it 3.07^. But there is 

 here so close a correspondence between experiment and 

 calculation, that no doubt can remain as to the correctness 

 of the basis on which the latter rests, or that the formula 

 already arrived at represents correctly the constitution of the 

 oil. 



These experiments were made in the winter of 1839, and 

 Dr. Apjohn stated that he was then under the impression 

 that the oil in question was a new substance, or rather one 

 which had not been previously described. Some months 

 after, however, upon looking over the second part of Pro- 

 fessor Graham's Elements of Chemistry, he was surprised 

 to find (in a table of the volumes of atoms in the gaseous 

 state,) mention made of a substance under the designation 

 of " oil of the ardent spirits from potatoes," to which was 

 attributed the very same formula, and density of vapour, 

 which he had found to belong to the oil of corn whiskey, 

 given him by Mr. Scanlan. Anxious to investigate the 

 matter further, and to ascertain whether the two oils were cer- 

 tainly the same. Dr. Apjohn looked into Dr. Thomson's fifth 

 volume on Organic Chemistry, and found there (page 481) 

 a notice of the potato oil, with a reference to the 30th and 

 56th volumes of the Annales de Chimie, in the former of 

 which its origin and properties are described by Pelletan, 

 and in the latter of which its analysis is given by Dumas. 

 Upon perusing these papers, his suspicions as to the identity 

 of the two oils were confirmed. In composition and proper- 

 ties they are the same; the only difference being, that Pelletan 

 represents the potato oil as having the specific gravity .821, 

 whereas Dr. Apjohn found that of the corn oil but .813, — a 



