210 PROCEEDINGS OF THE AMERICAN ACADEMY. 



I. 0.1275 gram of the substance gave on combustiou 0.2940 gram of 

 carbonic dioxide and 0.0436 gram of water. 

 II. 0.0608 gram of the substance gave 0.1401 gram of carbonic dioxide 



and 0.0230 gram of water. 



The substance is obviously the same as that previously analyzed, although 

 not so pure. 



We have, therefore, four analyses of three samples of this substance 

 prepared or purified in different ways, and, as these agree, there can be 

 no doubt that the black alteration product of the orthoquinone is a defi- 

 nite compound, and has the composition C12H8O5. 



Properties of the Black Alteration Product of Orthohenzoquinone 

 (^Orthodioxyphenyloxyorthoquinone,* C6H3(OH).2C6H20H02). — It forms 

 an almost black amorphous powder, which does not melt, but decomposes 

 gradually at temperatures above 170°. It is easily soluble in cold alco- 

 hol, ether, or glacial acetic acid ; insoluble in benzol or chloroform, 

 whether cold or hot. Strong acids have no apparent action on it, but 

 alkalies dissolve it. 



The following experiments were undertaken to determine the constitu- 

 tion of the black alteration product. 



Reduction of the Alteration Product. 



The formula of the substance CioIIgOs indicates that it contains two 

 benzol rings, and these may either be united directly, forming a diphenyl 

 compound, or they may be united by two atoms of oxygen, forming a 

 substituted pyrocatechine ether, [C6H30H]02[C6H2(OH)2]. The di- 

 phenyl formula, (HO)02H2C6-CeH3(OH)2, is rendered probable by the 

 formation of the dinaphthyldiquinhydrone t under somewhat similar cir- 

 cumstances from beta-naphthoquinone, which has been proved to be a 

 dinaphthyl compound ;t the pyrocatechine ether formula, on the other 

 hand, is in harmony with a derivative of tetrabromorthoquinone, which is 

 described later in this paper. Reduction seemed the easiest way to de- 



* This name and formula for the substance are established by the work 

 described later in this paper. 



t Ann. Chem. (Licbig), CXCIV. 205. 



X Ibid. 206. Korn Ber. d. cliem. Ges., XVII. 3020. 



