198 PROCEEDINGS OF THE AMERICAN A< ADEMY. 



nitric acid, whereas the triclilor- or tribrom-homopyrocatechine gives under 

 the same conditions an orthoquinone; and also by some experiments 

 undertaken by II. A. Torrey and on • of us on the action of hydric diox- 

 ide or electrolytic oxygen on pyrocatechine, which Led to unpromising 

 black products. Accordingly wo searched lor a method which would 

 produce a quinone without the use of mi oxidizing agent, and found one 

 in the action of iodine on the lead -ah of the dioxybenzol. After having 

 shown that the method converted hydroquinone into (juinone, we applied 

 ii rhino; hut our first experiments led to no result, because 

 we used alcohol as our Bolvent, which attacks the orthoquinone as soon 

 as it is Formed. Upon replacing the alcohol by chloroform we succeeded 

 in obtaiuing a dark garnet red solution, in which the presence of ortlm- 

 benzoquinone v tblished by a number of t' sts given later in this 



paper. 



From this solution we next tried to isolate the solid orthoquiuone, but 

 after trying every method we could devise, which gave even a remote 

 promise of >u ee. ■>-, we have failed to obtain a trace of solid orthoquinone, 

 and are forced to the opinion that it cannot exist in the Bolid -t ;itt-, or 

 even for any length of time in solution. The products obtained in place 

 of the orthoquinone in every case were a black substance insoluble in 

 chloroform, and a brown substance, or mixture of substances, which dis- 

 solved in chloroform : this brown product we have not attempted to inves- 

 • gate, hut we have studied the black insoluble product, and can give a 

 fairly complete account of its nature in spite of its unmanageable proper- 

 ties. It begins to form in the chloroform solution of the orthoquinone in 

 less than an hour, and is liest obtained by allowing the solution to Btand in 

 a corked flask for not more than thirty hours. A combustion of the bud- 

 stance gave results corresponding to the formula Ci 8 H 8 : , ; the analysis of 

 a lead Ball prepared in a somewhat different way indicated the same for- 

 mula, and this was confirmed by two analyses made by II. A. Torrey ol 

 his product from the electrolytic oxid ition of pyrocatechine, which Beemed 



to be identical with ours, and by an analysis of the benzoyl derivative of 



our black Bubstance; we have, therefore, five analyses of four different 



samples, all of which agree with each other, and leave no doubt that the 

 itance is a definite compound, and has the formula (', I UK. This 



formula indicate, that the compound was for d by the union of two 



molecule- of orthoquinone with the introduction of an additional hydroxy] 

 group, a view which La confirmed by the analysis of the had Ball 



I II OjPb, in which there are evidently two benzol rings to each atom 



of 1- el. When we consider the manner in which the-,, two benzol ri 



