214 PROCEEDINGS OF THE AMERICAN ACADEMY. 



tiou of chlorpyrocatechine under these conditions is confirmed by the 

 following analysis of the lead salt, made by adding plumbic acetate to an 

 aqueous solution of the product of the reaction of hydrochloric acid on 

 the solution of orthoquinone. 



0.3867 gram of the salt gave .03306 gram of plumbic sulphate. 



Calculated for ■d'„„_j 



CoHjClO^Pb. ^°'^°'^- 



Lead 58.98 58.55 



Tlie mouochlorpyrocatechine in the slightly impure state in which we 

 obtained it crystallized in white pearly plates, which are easily soluble 

 in water, alcohol, ether, benzol, chloroform, or acetone ; insoluble ia 

 ligroin. With an aqueous solution of plumbic acetate it gives a lead 

 salt. It blackens quickly if exposed to the air after treatment with 

 an alkali. The melting point observed by us is of course of no value, 

 on account of the presence of the impurity of pyrocatechine. 



Behavior of the Solution of Orthohenzoquinone with Reducing Agents. 



Amnionic Sulphide. — Some of the solution of orthoquinone in chloro- 

 form was shaken with about one third of its volume of the ordinary 

 laboratory solution of amnionic sulphide. The red color of the ortho- 

 quinone disappeared, and the aqueous solution took on a dark color. 

 The two liquids were separated by means of a drop funnel, and the 

 chloroform was extracted twice with water, the extracts being added to 

 the amnionic sulphide solution at first obtained. The mixed aqueous 

 portion was then heated on the steam bath, acidified with hydrochloric 

 acid, allowed to stand until the precipitated sulphur had settled, filtered, 

 and the clear dark colored filtrate extracted with ether. The residue 

 left on the evaporation of the ether was recrystallized twice from benzol, 

 when it was found to melt constant at 103° -104°, and to show all the 

 other properties of j)yrocatechine. In order to be certain that the pyro- 

 catechine, detected in the product from the action of ammonic sulphide 

 on the orthoquinone solution, was formed from the orthoquinone, it was 

 necessary to prove that this solution contained no free pyrocatechine ; 

 for this purpose a small amount of it taken before the reduction was 

 shaken with water, the water evaporated, and the residue extracted with 

 benzol ; the benzol extract was evaporated to drj'ness, the very slight 

 residue dissolved in water, and tested with plumbic acetate, when it 

 gave no precipitate, showing that no free pyrocatechine was contained in 

 the chloroform solution. 



