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, 
