108 Profieedings of the Royal- Irish Academy. 



<jhloric acid, the mixture rapidly turned a dark red colour, and after three of 

 four days standing in a stoppered flask, at the temperature of the laboratory, 

 crystals began to separate. When the reaction had finished, the solid, which 

 weighed about 3 grams, was filtered and recrystallised from a mixture of 

 chloroform and alcohol. It melted at 158° C, about two degrees higher than 

 the compound CosHjoO obtained from methyl-ethyl-ketone and benzal- 

 dehyde, but a mixture of the two substances, also melted at 156-158° C. 

 The two compounds are, therefore, identical. 



3. Action of Benzaldehyde on Ethyl- Acetoacetic Ester. 



Benzylidene-ethyl-acetoacetic acid, CH^CH : CH • CO • CEC^HsCOOH, 

 was obtained by condensing benzaldehyde with etbyl-acetoacetic ester in the 

 presence of dilute alkali. 



A solution of 5 c.cs. of ethyl-acetoacetic ester, 8 c.cs. of benzaldehyde, and 



3 grams of sodium hydroxide in 100 c.cs. of dilute alcohol, was left for one 

 month in a stoppered flask at the laboratory temperature. Without removing 

 the crystals, which had separated, the mixture was extracted with ether, and 

 the aqueous alkaline layer was then acidified with hydrochloric acid. About 



4 grams of a colourless crystalline acid were obtained. It melted with 

 decomposition at 152° C, and gave on analysis the following results : — 



0-2176 substance gave 0-5712 CO, and 01247 H,0 

 corresponding to < ' 71-59 H 6-37 

 C„H„0, requires C 71-56 H 6-42 



