purpurin

[Lat. purpur ( a ); -in. ] Chem.: C20H12O7. Oxyalizaric acid. A red coloring matter obtained from madder in the same way as alizarin. It may be separated from the alum liquid from which the alizarin has deposited, by adding sulphuric acid, and washing out the alumina by hydrochloric acid from the precipitated pur purin. It crystallizes from alcohol in red or orange colored needles, di olves in alcohol and ether, and is more soluble in water than alizarin. It di olves in boiling alum water and in caustic alkalies, forming bright red solutions, and is le easily attacked by nitric acid than alizarin. pür-pür-ox-ăn-thic, adj. [English purpurox anth(in); -ic.] Derived from or containing purpuroxanthin. purpuroxanthic-acid, 8. Chem.: C15H3O6 = C14H;O4, CO2H. An acid ob tained by boiling purpurin in a solution of alum. It is slightly soluble ble in water, soluble in hot alco hol, from which it crystallizes in yellow needles, and melts at 231°. At a higher temperature it splits up into carbonic acid and purpuroxanthin.