Perezia Root.—This root is obtained from several Mexican plants, Perezia Wrightii A. Gray, P. Nana A. Gray, and P. Dugesii A. Gray. (Fam. Compositae.) It contains pipitizahoic acid, a substance which crystallizes in beautiful golden-yellow needles. R. Anschutz and J. W. Leather obtained from the dried roots of P. adnata A. Gray (Trixis Pipitzahoac Schaffner), an average of 3.6 per cent. of this acid, which melts at from 103° to 104° C. (217.4°-219.2° F.), sublimes readily, and is easily soluble in alcohol, ether, chloroform, benzene, and glacial acetic acid. The authors confirm the formula given to the acid in 1855—viz., C15H20O3. It is a quinone, and bears great resemblance, when recrystallized from diluted alcohol, to oxythymoquinone, which, recrystallized from the same liquid, is scarcely distinguishable from it. (A. J. P., 1884, 185, and Ph. Rund., 1883, 245; A. Pharm., 1887, 183.)
Under the name of perezol the 0.5 per cent. alcoholic solution of pipitzahoic acid has been recommended by Duyk as an alkalimetrical indicator. By acids it is at once decolorized; with alkalies it becomes reddish. Boric, and perhaps other acids, and acetates, borates, bicarbonates, and carbonates act with respect to the solution like alkalies. For a paper on pipitzahoic acid by Altamirans, see Analen del Institute Mex., Nat. 7, p. 21, or P. J., 1905, 553.