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 freezing mixture ; pre- 

 cipitation with ligroin at— o ; precipitation with tetrachloride of carbon at 

 —20°; we bad great hopes of this la>t 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 orthobenzoquiuoue cannot 

 exi.>t for any length of time, if at all, in the solid state. 



Study of the Alteration Product of Ortiiobenzoquinone. 



This substance was most conveniently obtained by allowing the chloro- 

 form solution of orthobenzoquiuoue, 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 filtering 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- 

 Btance, after it had been purified by extraction with benzol, was dried til 

 ;■</<•,/,, and analyzed with the following results: — 



0.2" 11 gram of the substance gave on combustion 0.4G84 gram of car- 

 bonic dioxide and 0.0696 "ram of water. 



i f'.r Calculated for «._. . 



I ii "ii ',ii ■ ■ 



Carbon 66.67 62.07 62.59 



Hydrogen 8.70 8.45 8.79 



Thee numbers would indicate thai the Bubstance has been formed b\ 

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



• l in- solution ihould not be allowed to itand more than thirty hours, as in tlmt 

 case the product is contaminated with a brown Imparity. 



