240 ON METHYL-ALIZARINE AND ETHYL- ALIZARINE. 



converted into alizarine by the action of fusing potassic 

 hydrate, though remaining unchanged when heated with 

 strong alkaline lyes. The actions of the two on the spec- 

 trum when in solution are very similar. Both are inca- 

 pable of dyeing mordants. 



The quantity of material at my disposal barely sufficed 

 for the determination of the composition of methyl-ali- 

 zarine. The results of analysis, however, leave, I think, 

 no doubt as to its true formula. 



0*2738 grm. methyl-alizarine, dried at 140 C, gave 

 0*7034 grm. carbonic acid and 0*1082 water. 



These numbers lead to the following composition : — 



Calculation. 



, * s Experiment. 



C 15 180 70*86 70*06 



H 10 10 3*93 4*39 



4 64 2521 25*55 



254 IOO'OO 100*00 



0*4710 grm. of the crystallized potassium compound of 

 methyl- alizarine, prepared in the manner above described 

 and dried in vacuo, lost, on being heated for several hours 

 at 110 C, 0*0022 grm., and then gave 0*1318 grm. sul- 

 phate of potassium containing 0*0590 potassium = 12*60 

 per cent. The formula C I4 H 6 (KO)(CHjO) O z requires 

 13*35 per cent, of potassium. 



The formula of methyl-alizarine must therefore be 

 C 14 H 6 (HO) (CHjO) 2 ; and hence it would appear to 

 belong to the class of compound ethers, being formed by 

 the replacement of one of the hydrogen atoms of a bibasic 

 acid by methyl. It has a composition similar to that of 

 Mr. Perkin's diacetyl-alizarine. In the latter, however, 

 two atoms of hydrogen are replaced by acetyl. Diacetyl- 

 alizarine seems also to be a much less stable body than 

 methyl-alizarine. 



Ethyl-alizarine was prepared in the same way as the cor- 



