88 



seemed to me that it might be of some interest to ascertain 

 the nature and properties of the methylic and ethylic sub- 

 stitution products of alizarine obtained directly from the 

 latter. 



In order to obtain methyl-alizarine I tried several 

 methods. The first consisted in heating bromalizarine with 

 iodide of methyl and metallic silver in closed tubes. This 

 process yielded a small quantity of a crystalline substance, 

 which I believed to be the compound sought for. The other 

 method, which is one now often practised for obtaining 

 methylic and ethylic substitution products, gave better 

 results. 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 

 emptied, and the excess of iodide of methyl having been 

 evaporated, the residue was treated first with hot water, to 

 remove the iodide of potassium, and then with a little cold 

 alcohol. The alcohol — which dissolved out a brown resinous 

 impurity — having been filtered off*, the residue was treated 

 with dilute caustic potash lye, in which the alizarine not 

 acted on dissolved with a violet colour. The liquid having 

 been filtered off", the residue, which consisted of the potassium 

 compound of methyl-alizarine — a compound very little 

 soluble in cold water — was washed until the percolating 

 liquid began to be of a cherry-red colour. It was then 

 treated with hydrochloric acid, and the orange-coloured 

 flocks left undissolved were filtered off", washed and dissolved 

 in boiling alcohol. The alcohol, on cooling, deposited crys- 

 talline needles of methyl-alizarine. 



Methyl-alizarine as thus prepared has the following pro- 

 perties : — When crystallised from boiling alcohol it appears 

 in long yellow needles, having a reddish tinge, but without 

 the semi-metallic lustre peculiar to alizarine which it gene- 

 rally resembles. When heated it is entirely volatilised, 



