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of loss to the manufacturer. The isomerides of alizarine 
hitherto observed are the following : — 
1. Purpuroxanthine, a body first obtained by Schiit- 
zenberger from commercial purpurine, and afterwards 
prepared artificially by the action of reducing agents on 
purpurine. It crystallises in yellow needles, soluble in 
alkalies with a blood-red colour. 
2. Isoalizarine, a substance derived from madder and 
described by Rochleder, having properties very similar to 
those of purpuroxanthine, and perhaps identical with it. 
3. Frangulic Acid, a substance also very similar to pur- 
puroxanthine, obtained by Faust by the decomposition of 
franguline, a constituent of the bark of Rhamnus frangula. 
4. Anthraflavic Acid or A nthraflavine, a body accompany- 
ing artificial alizarine, first described by one of the authors in 
a paper read before this Society,* and subsequently examined 
by Mr. Perkin. Its isomerism with alizarine was established 
by Mr. Perkin, who was the first to obtain it in a state of 
perfect purity. It is easily distinguished by the colour 
of its alkaline solution, which is yellow. 
5. Anthraflavon, a product obtained by the action of 
diluted sulphuric acid on oxybenzoic acid. We have not 
yet had an opportunity of preparing and examining this 
body, but on reading the description of it given by its 
discoverers, Barth and Sennhofer, it is evident that it bears 
a strong resemblance to the preceding. 
G. Quinazarine , obtained by Baeyer, by the action of 
phthalic acid on hydroquinone. Of all the isomerides it 
most resembles alizarine itself. Its alkaline solutions have 
the same violet colour as those of alizarine, and it dyes 
mordants, while the other isomerides have no tinctorial 
properties. 
i . Chrysazine , a body formed by the action of nitrous 
acid on hydrochiysammide, and carefully examined by its 
* Memoirs, 3rd Series, Vol. V., p. 227. 
