141 
prepared from nearly perfectly pure anthraquinone, which 
had been distilled and crystallised from benzol. 
Another point remains to be considered in connection 
with this subject. It is well known that the beautiful dis- 
covery of the mode of forming alizarine was the direct 
result of a previous one, viz. : that of the reduction of the 
natural product by means of metallic zinc to anthracene. 
The question therefore naturally suggested itself: what is 
the nature of the hydrocarbon formed by the same process 
from anthraflavic acid ? Is it anthracene or something else ? 
In order to decide this question I took a quantity of the 
acid and heated it with 50 times its weight of zinc powder, 
in the manner described by Grabe and Liebermann. I ob- 
tained a quantity of a brownish crystalline sublimate, 
amounting to about 10 per cent of the acid employed, which 
was purified by sublimation and washing with ether. It 
still retained the yellowish tinge which, according to Grabe 
and Liebermann, adheres so pertinaciously to anthracene, 
but it did not differ in other respects from the pure substance. 
It melted at the same temperature as anthracene, and began 
to sublime before fusing, it dissolved in boiling alcohol, but 
more readily in benzol, and was deposited from these solu- 
tions in lustrous crystals of a very regular form, and it gave, 
like anthracene with picric acid, a compound crystallizing 
in long red needles. I wish to speak with some reserve on 
this point, as the quantity of material at my disposal was 
not sufficient for an analysis, but should it turn out that my 
product is identical with anthracene, this fact would throw 
doubt on some of the reasoning of Grabe and Liebermann, 
who assume that if an organic substance yields a definite 
hydrocarbon by the action of metallic zinc, the latter con- 
tains the same number of atoms of carbon as the original 
substance. 
The President stated that in looking over the Memoran- 
