OF ARTS AND SCIENCES. 69 



nanthrene by heat. By passing a mixture of ethylene and diphenyl 

 through a red-liot porcehiin tube, however, he obtained a large quan- 

 tity of phenantlirene, and also by heating liquid ditolyl or stilbene to 

 dull redness in a sealed tube. Finally Kramers * found a trace of 

 phenantlirene among the products from passing phenol through a yel- 

 low-hot tube. 



Constitution of Anthracene and Phenanthrene. 



Dumas and Laurent, in their first article on anthracene, considered 

 it a polymerized naphtaline. Anderson, after establishing the formula, 

 called attention to the fact that antliracene and anthrachinone differed 

 from stilbene and benzil only by two atoms of hydrogen in each case. 

 Berthelot, in 1867, on account of its formation from toluol at a red 

 heat, gave it the formula C|,IT^[CyH^C.,H„],t which he showed later 

 in the same year was supported also by Limpricht's synthesis, and 

 his own decompositions of anthracene % with hydriodic acid ; he 

 considered it an " acetylodiphenylene," but pointed out the fact 

 that, while the calculated boiling-point of this substance should be 

 310°-320°, the boiling-point of anthracene is in reality 360°. 



In 1870, Graebe and Liebermann proposed two formulas for anthra- 

 cene, giving the preference to No. 1, on the ground of the syntheses 



No. 2. 

 H H 



I I 

 HC— CH 



I I 



HC CH 



C — c 



H H 



by Limpricht from benzylchloride, and Berthelot from styrol and 

 benzol ; also because this formula is like that of naphtaline, which 

 they show is allied to anthracene in many respects ; but these argu- 

 ments were overturned in 1872 by the discovery of phenanthrene, 



* Ann. Chem. Pliarm., clxxxix. 132. 

 t Calculated to modern atomic weights. 

 X Bull. Chem. Soc, ix. 2%. 



