206 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Experimental Part. 

 Action of Iodine on the Lead Salt of Hydroquinone. 



These experiments were tried to test the efficacy of this method of 

 makin"' quinones. An aqueous solution of ten grams of hydroquinone 

 was ti'eated with the calculated amount of sodic hydrate in a flask, to 

 which the air had access only through a tube containing an alkaline 

 solution of pyrogallol ; to the sodium salt thus formed an aqueous solution 

 of plumbic acetate was added, which gave a white precipitate of the lead 

 salt. As this blackened rapidly on exposure to the air, no attempt was 

 made to filter it, but an alcoholic solution of five grams of iodine was 

 added directly to the precipitate suspended in the liquid, when plumbic 

 iodide was formed, as shown by the appearance of a yellow color. After 

 the reaction seemed to have come to an end, the insoluble substances 

 were filtered out, and the filtrate, which had a strong odor of quinone, 

 extracted with ether. This ether extract left on evaporation yellow 

 crystals with a strong odor of quinone, which under the microscope 

 showed the characteristic form of this substance, and after purification by 

 sublimation melted at 11 2° -11 3°, which, although distinctly below the 

 melting point of quinone, 115°. 7, is near enough to it to prove in con- 

 junction with the otlier properties that quinone was formed. 



To prove that this quinone was formed by the action of the iodine on 

 the lead salt and not by the oxidizing effect of the air, a specimen of the 

 salt mixed with water was exposed to the air for several hours, until it 

 was thoroughly blackened ; upon filtration a red solution was obtained 

 which had no odor of quinone. Extraction with ether did not remove 

 the red color, and on the evaporation of the ether, crystals of hydroqui- 

 none were obtained, recognized by the melting point, but no quinone. 

 Upon adding an alcoholic solution of iodine to a similar specimen of 

 the lead salt blackened by exposure to the air, the sharp odor of qui- 

 nine was observed at once, and a considerable amount of this body was 

 obtained from the filtrate. The method, therefore, is applicable to the 

 production of quinones, but naturally would be used only in cases where 

 oxidation is inadmissible. 



We also tried some experiments with iodine and the lead salt of resor- 

 cine, but as it was evident that the purification of the product would be 

 a matter of great difficulty, we have postponed the continuation of this 

 work until we have finished the study of pyrocatechine. 



