OF ARTS AND SCIENCES. 219 



The Action of Bromine Water on Pyromucamide. 



Some remarkable color reactions observed by Professor Hill, when 

 studying the action of bromine and potassium hydroxide on pyro- 

 mucamide, led to the suggestion that interesting results might be 

 obtained in that direction by further work. The author therefore 

 gave a short time to the study of the nature of these color reactions, 

 as well as those produced when bromine water is used in place of 

 pure bromine, and when other basic substances are used in place of 

 potassium hydroxide. 



Pyromucamide treated with bromine water dissolves readily, 

 producing a solution almost or quite colorless. This was treated 

 in various ways in order to isolate, if possible, some definite sub- 

 stance from it, but amorphous dark products were always obtained. 

 If to the fresh solution there is added almost any strongly basic 

 inorganic substance, a dark blue (or sometimes purple) color is 

 soon produced, the rapidity of its production depending apparently 

 on the strength of the base. The color usually changes to purple 

 in a short time, and afterwards undergoes other alterations, gener- 

 ally passing to red, and finally, if the amount of pyromucamide 

 used is small, fading to pale yellow. When the base employed is 

 barium hydroxide, a dark blue amorphous precipitate is produced. 

 An investigation was made as to the quantity of bromine required 

 to produce the maximum intensity of color from a given amount of 

 pyromucamide. Measured quantities of dilute solutions of pyro- 

 mucamide and bromine were mixed, shaken, and allowed to stand 

 a few moments. Then an excess of sodium hydroxide was added, 

 and the colors produced were compared. It was found that two 

 atoms of bromine to each molecule of pyromucamide gave the deep- 

 est color on subsequent treatment with alkali. Either a deficiency 

 or an excess of bromine is unfavorable to the color production. 

 The dark blue compound was too unstable for isolation. 



The production of this color may serve as a very delicate test for 

 pyromucamide. When one milligram of the amide is dissolved in 

 a drop of dilute bromine water, and the solution made alkaline, 

 the blue (or purple) color produced is quite distinct. 



Chlorine water can be used instead of bromine water, but the 

 color was not obtained when iodine or nitric acid was emplo3 r ed. 

 Substituted pyromucamides, so far as investigated, do not give the 

 color reaction: S-methylpyromucamide, )3S-dibrompyromucamide, 

 and /3y-dichlorpyromucamide were tried. 



