[ 216 ] 



XXII. 



ON THE VALUE OF BENZIDINE FOR THE DETECTION OF 

 MINUTE THACES OF BLOOD. 



By E. J. McWEENEY, M.A., M.D. (RU.I.) ; D.P.H. ; F.E.C.P.I. ; 



Professor of Pathology and Bacteriology in the Catholic University School of 

 Medicine, Dublin. 



[Read June 22. Ordered for Publication July 13. Published August 14, 1909.] 



Benzidine, the graphic formula of which is here presented, 



CH— OH CtI = OH 



// %. / \ 



NUo— C C— C C-H,N 



\ /-%.// 



CH=CH CH— Cli 



is di-;j-diamino-diphenyl, first discovered by Zinin in 1845. It is a 

 colourless crystalline solid of melting-point 122° C 



Being closely allied to aniline, NHz . OeHi . H, wliieh by oxidation yields 

 coloured products (oxidation of a mixture of aniline and toluidine by PbOa 

 resulted in the discovery of the first aniline dye by Perkin in 1856), benzi- 

 dine might naturally be expected to behave similarly ; and J. Wolff (1) finds 

 that, when an acetic acid solution of benzidine is treated with PbOs, a 

 beautiful blue colour is at once formed. 



Allied to benzidine is dipheno-quinone, 



I — CoHi — CgH4 — 1 



0, 



which is the motlier-substance of cserulignon (2), 

 OeH,(OCH3X-CeH,(OCH3). 



Lo h 



cferulignon, 

 a violet-blue powder, which is obtained in the purification of pure wood- 

 vinegar, the relation being somewhat analogous to that which holds between 

 aniline and its oxidation-product, quinone. 



NIL.CeH4.H, p-CeH,-T 



.,! ' O O-J 



aniline. 



quiuone. 



