216 Proceedings of the Royal Irish Academy. 



in a crystalline state by addition of alcohol. After a few recrystallizations 

 from chloroform and alcohol it melted at 191° C, and gave on analysis the 

 following results : — 



0-2592 substance gave 07220 C0 2 and 01144 H,0, 



corresponding to C 75-97, H 4-90, 



C a -Ha,0 5 requires C 76-33, H 4-75. 



It crystallizes from chloroform and alcohol in yellowish, hexagonal plates, 

 which are sparingly soluble in cold or hot alcohol, and readily soluble in 

 chloroform. 



The crystals are coloured a dark red on contact with concentrated 

 sulphuric acid, in which they dissolve, forming a cherry-red solution. 



6. Action of Piperonal on Methylethylketonc in the Presence of Alcoholic 



Hydrochloric Acid. 



A solution of 8 c.cs. of methylethylketone and 32 grams of piperonal in 150 

 c.cs. of alcoholic hydrochloric -acid rapidly turned a dark-blue colour, which 

 gradually changed to purple. After standing a few days in a stoppered flask 

 a tarry product separated. From the latter, by treatment with chloroform 

 and alcohol, a bluish solid was obtained. 



On mixing with dilute potash the blue colour, which was apparently due 

 to a hydrochloric acid addition compound, or to an oxonium salt, disappeared. 

 The substance was recrystallized several times from chloroform and alcohol. 

 "When dried at 110° C, it melted at 212° C, and gave on analysis the following 



results : — 



0-1442 substance gave 0-3802 C0 2 and 0-0596 H 3 0, 

 corresponding to C 71*9, H 4 - 6, 

 I '.-HooO, requires C 71"8, H 4-3. 



The substance crystallizes in long, colourless, rectangular prisms, which 

 are very sparingly soluble in ether, benzene, or alcohol, and soluble in 

 chloroform. 



The crystals are coloured dark red on contact with concentrated sulphuric 

 acid, in which they dissolve, forming a deep-red solution. 



