136 
ing it the residue was treated first with water, and then 
with cold alcohol. It was then dissolved in dilute caustic 
soda, and to the boiling solution chloride of barium was 
added. The filtered liquid deposited on cooling a mass of 
small shining crystals of the barium salt of the acid. These 
were purified by recrystallisation from boiling water, and 
then treated with hydrochloric acid. The lemon-yellow 
flocks left by the acid were filtered off, washed, and dis- 
solved in a little boiling alcohol. This on cooling deposited 
a quantity of yellow silky needles, consisting of the acid, 
which I have named Anthvaflavic Acid, in order to indicate 
its source and its most obvious external property. 
The chief properties of this acid are these : — When crys- 
tallised from alcohol and dried, it has the appearance of a 
dark lemon-yellow silky mass, which under the microscope 
is seen to consist of slender four-sided prisms. When heated 
on platinum foil it gives off copious yellow fumes and then 
burns with a luminous flame without leaving any residue. 
When cautiously heated in a tube or between two watch 
glasses, it may be almost entirely volatilised, yielding a 
vapour which condenses in the form of a yellow sublimate. 
This sublimate consists of small lusti’ous crystalline plates, 
which, examined under the microscope, exhibit very regular 
outlines. The acid is only slightly soluble in boiling water, 
and almost insoluble in cold. It is more soluble in alcohol 
and ether, but insoluble in boiling benzol and sulphide of 
cai'bon. It dissolves readily in concentrated sulphuric acid 
even in the cold, forming a dark yellow solution, from which 
it is precipitated by water in yellow flocks. It is not much 
affected by dilute nitric acid even on boiling. With fuming 
nitric acid it yields a so-called nitro-acid, to which I shall 
return presently. 
It is the fact of this substance yielding with bases com- 
pounds of well defined character, some of them being regu- 
larly crystallised, that entitles it more especially to be 
