METHYL- ALIZARINE AND ETHYL-ALIZARINE. 237 



from some of the u by-product," from which the alizarine 

 had already been separated before I received it from Mr. 

 Perkin, and purified with great care, gave exactly the 

 same composition as before. 



Graebe and Liebermann* have also examined a yellow 

 crystalline body accompanying artificial alizarine, which 

 is converted into the latter by the action of fusing caustic 

 potash. They are of opinion that it is identical with 

 anthraflavic acid, there being, indeed, little or no difference 

 in the properties of the two substances. They assign to 

 it the formula C, 4 H 8 O v and consider it monoxyanthra- 

 quinone, alizarine being dioxyanthraquinone. The results 

 of their analyses of the substance and its barium com- 

 pound differ, however, so widely from those obtained by 

 Mr. Perkin and myself, especially as regards the number 

 of atoms of hydrogen that may be replaced by metals, as 

 to lead to the conclusion either that there exist more 

 than one body having the general properties (chemical 

 and physical) of anthraflavic acid, or that we have not all 

 been working with pure substances. 



Without pronouncing any decided opinion on this point, 

 which can only be determined by further investigation, 

 and without entertaining any sanguine anticipation of 

 being able to prepare anthraflavic acid directly from ali- 

 zarine, it seemed to me that it might be of some interest 

 to ascertain the nature and properties of the methylic and 

 ethylic compounds of alizarine obtained directly from the 

 latter. 



In order to prepare methyl-alizarine, purified artificial 

 alizarine was treated with a mixture of iodide of methyl, 

 caustic potash, and a little methylic alcohol in closed 

 tubes, at a moderate temperature. After heating for 

 some days the tubes were opened ; and the excess of iodide 

 of methyl having been evaporated, the residue was treated 



* Liebig's 'Annalen,' vol. clx. p. 141. 



