4 Proceedings of the Royal Irish Academy. 



The fact that both products were soluble in potash pointed to formulae II 

 as correct ; hut, contrary to what one would expect from readily 

 enolisable substances of such formulae, neither yielded in alcoholic solution a 

 colouration with ferric chloride, nor did they colour concentrated sulphuric 

 acid. 



To decide the matter we methylated cinnamyl-acetyl-methane. In this 

 way a substance was obtained having beyond all doubt the composition 



C 6 H 5 CH : CH . CO . CH(CH 3 ) . CO . CH 3 . 

 It differed materially from the compound obtained from methyl-ethyl-ketone. 

 For instance, its melting-point was nearly 80° C. lower, it yielded a dark- 

 green colouration with ferric chloride, it crystallized in long delicate needles 

 of a light-yellow colour, whereas the methyl-ethyl-ketone compound 

 crystallized in short, colourless prisms. Hence the only possible formula for 

 the latter compound is 



C,H s O LI : CH . CO . CH 2 . CO . CH 2 . CH„ 

 and from its close resemblance to the methyl-isopropyl derivative we may 

 infer that the latter has the constitution 



/CH 3 

 C 6 H 5 CH : CH . CO . CH, . CO . CH ; 



\CH 5 



in other words, that in both cases condensation took place on the methyl- 

 group. 



The diketones obtained from ethyl-methyl-ketone and methyl-isopropyl- 

 ketone vary in several points from those obtained from acetone and 

 acetophenone : for instance, in their greatly diminished solubility in ether, in 

 their almost complete insolubility in petroleum ether, in not being precipitated 

 by carbon dioxide from their alkaline solutions, whilst their colouring power 

 for wool mordanted with iron is hardly perceptible. 



Experimental Paet. 



Cianamyl-acetyl-methane, C 8 H 5 . CH : CH . CO . CH 2 . CO . CH S . 



42 grms. of methyl cinnamate were dissolved in 17 c.c. of acetone, and 

 7"5 grms. of sodium wire were slowly added during the course of some 

 hours, care being taken not to let the temperature of the mixture rise much 

 above that of the laboratory. The mixture was kept continually shaken, 

 and when it began to get too thick, absolute ether or petroleum ether was 

 added, and the mixture vigorously stirred. It was then allowed to stand over- 

 night. On the following morning more ether or petroleum ether was added 



