METHYL-ALIZARINE AND ETHYL-ALIZARINE. 239 



obscuration of the parts of the spectrum adjacent to the 

 band. On adding alcoholic potash solution to a boil- 

 ing alcoholic solution of methyl-alizarine, the potassium 

 compound is deposited, on cooling, in dark-red needles 

 arranged in star-shaped masses. The sodium compound, 

 prepared in the same way, crystallizes in small light-red 

 needles, forming a bulky mass which fills the whole liquid. 

 In liquid ammonia and in baryta-water methyl-alizarine 

 dissolves very little even on boiling. A watery solution 

 of the potassium compound gives, with chloride of barium, 

 a red flocculent precipitate, and with sulphate of magne- 

 sium a bright pink precipitate. The alcoholic solution of 

 methyl- alizarine gives no precipitate with acetate of lead. 

 When treated with boiling nitric acid, methyl-alizarine is 

 dissolved and decomposed; and the solution, on evapora- 

 tion, leaves a white crystalline residue, which on being 

 heated yields a sublimate in white needles, consisting pro- 

 bably of phthalic anhydride. Methyl-alizarine undergoes 

 no change when treated with strong caustic potash lye, 

 even at the boiling-temperature. It is only when fusing 

 hydrate of potash is employed that decomposition takes 

 place. If the operation be carefully conducted, there will 

 be obtained, on the addition of water to the fused mass, a 

 violet-coloured solution, which shows the absorption bands 

 of alizarine very distinctly. There is no doubt, therefore, 

 that by the more energetic action of the alkali at the tem- 

 perature of fusion alizarine is regenerated. Methyl-ali- 

 zarine does not dye mordanted cloth when tried in the 

 usual manner. It imparts hardly any colour to the mor- 

 dants, differing in this respect from alizarine itself more 

 than in any other. 



Though methyl-alizarine differs in many points very 

 widely from anthraflavic acid, still the two substances 

 resemble one another in some respects. Both yield crys- 

 tallized potassium and sodium compounds. Both are 



