208 PROCEEDINGS OP THE AMERICAN ACADEMY. 



the orthoquinone ; evaporation by a stream of dry air, or dry carbonic 

 dioxide passed through the solution cooled by a freeziug mixture ; pre- 

 cipitation with ligroin at — 5° ; precipitation with tetrachloride of carbon at 

 — 20° ; we had great hopes of this last attempt, as we had not succeeded 

 in making any of the orthoquinone, when tetrachloride of carbon was 

 substituted for chloroform in the preparation, and we inferred from this 

 that the quinone probably was insoluble in this substance ; but this, as 

 well as all the other experiments mentioned above, did not lead to the de- 

 sired result. The product in every case was the black alteration product 

 already mentioned, the nature of which will be discussed presently, so 

 that we are forced to the conclusion that the orthobenzoquinone cannot 

 exist for any length of time, if at all, in the solid state. 



Study of the Alteration Product of Orthobenzoquinone. 



This substance was most conveniently obtained by allowing the chloro- 

 form solution of orthobenzoquinone, prepared as already described, to 

 stand at ordinary temperatures in a corked flask from twenty-four to 

 thirty hours.* The black precipitate thus formed was not easy to purify, 

 for although it was soluble in alcohol and some other solvents, all our 

 attempts to crystallize it have failed; we finally decided to depend for its 

 purification on its insolubility in chloroform and benzol. Accordingly, 

 after filterius it out from the chloroform in which it was formed, we 

 washed it thoroughly with chloroform, and afterward extracted it three 

 times with hot benzol. About 40 per cent of the orthoquinone used 

 was converted into this black product. In calculating this yield we 

 assumed that the amount of orthoquinone in the chloroform solution cor- 

 responded to the amount of iodine used in making it. The black sub- 

 stance, after it had been purified by extraction with benzol, was dried in 

 vacuo and analyzed with the following results : — 



0.2041 gram of the substance gave on combustion 0.4684 gram of car- 

 bonic dioxide and 0.0696 gram of water. 



to' 



Calculated for Calculated for Pnnnd 



C],H^0„(0H)2. Ci,H50o(OH)3. TUUUU. 



Carbon 66.67 62.07 62.59 



Hydrogen 3.70 3.45 3.79 



These numbers would indicate that the substance has been formed by 

 the union of two molecules of orthoquinone with the introduction of a 



* The solution sliould not be allowed to stand more than tliirty hours, as in that 

 case the product is contaminated with a brown impurity. 



