ON QUINONE. — WALLACE. 303 



This precipitate was filtered, washed with ether in which it 

 was insohible, and dried on a filter-paper. Tlie brown powder 

 remaining readily dissolved in ethyl and methyl alcohols and 

 acetone, forming a brown solution, which on evaporation left 

 a black enamel-like residue. It w^as insoluble in water, and 

 all other common organic solvents, but those mentioned 

 jibove. It .was impossible to obtain it in a crystalline form," 

 but a precipitation of it was obtained by adding w^ater to a 

 concentrated alcoholic solution and evaporating until little 

 or no alcohol remained. This process. was not satisfactory, as 

 the compound separated as a colloid in pure water. This sub- 

 stance was not further studied. The total yield from the 

 experiment was onl}^ about 0.5 gram. 



On evaporating the ethereal solution in a porcelain dish, 

 there remained a green crystalline substance in the central 

 part, with a brown amorphous mass surrounding it. The 

 crystals were removed and in order to obtain more of them 

 the amorphous mass was redissolved in ether and again evap- 

 orated. This mechanical process of separation was repeated 

 until a quantity of the crystals was obtained. They were 

 recrystallized from ether and a pure-looking product obtained 

 with a practically constant melting point of 170°C. 



An analysis gave the following results : 

 0.150] gram of substance gave 0.3645 gram CO, and 0.0609 

 gram H O. 



t'alculiited for Found. 



CoHioO^. I 



C 66.02^ 66.29^ 



H 4.63$^ 4.51$^ 



The green crystals gave tests for a qiiinhydrone ; the 

 analysis prove it to be of the formula (\o H,,, O, or ordinary 

 quinhydrone. 



The remaining amorjihous tarry residue left from the ether 

 solution consisted of free iodine, some quinhydrone and re- 



