90 



alkali at the temperature of fusion alizarine is regenerated. 

 Methyl-alizarine does not d^^e mordanted cloth when tried in 

 the usual manner. It imparts hardly any colour to the 

 mordants, and differs, therefore, in this respect from the 

 parent substance more than in any otlier. 



Though methyl-alizarine differs in most points very 

 widely from anthraflavic acid, still the two substances are 

 found to resemble one another as regards some of their pro- 

 perties. Both yield crystallised potassium and sodium 

 compounds. Both are converted into alizarine by the action 

 of fusing potassic hydrate, though both remain unchanged 

 when treated with strong alkaline lyes. The action of both 

 on the spectrum is very similar. Neither of them is preci- 

 pitated from its alcoholic solution by acetate of lead. Both 

 are incapable of dyeing mordants. 



The analysis of methyl-alizarine gave numbers corre- 

 sponding with the formula C15H10O4. It is therefore aliza- 

 rine in which one atom of hydrogen is replaced by methyl. 

 It still remained to determine how this substitution takes 

 place, whether it is one of the two hydrox^d atoms con- 

 tained in alizarine the hydrogen of which is replaced by 

 methyl, or whether the substitution is effected in a different 

 manner. In the former case methyl-alizarine would con- 

 tain only one atom of hydrogen replaceable by metals. The 

 formula of methyl-alizarine being Ci4Hg(HO)(CH30)02, 

 that of the potassium compound, for instance, would be 

 Ci4H6(KO)(CH30)02 and it would contain by calculation 

 13'3 per cent of potassium. Now the potassium compound 

 prepared in the manner just described and dried first over 

 sulphuric acid and then at 180° C, was found to contain 

 12*6 per cent of potassium. It is certain therefore that 

 methyl-alizarine belongs 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 similar com- 

 position to Mr. Perkin's diacetyl -alizarine. In the latter 



