diazo-

(di-az'o) [G. di-, two, -{- Fr. azote, nitrogen.] A prefix denoting a compound containing two linked nitrogen atoms, united to an aromatic group and to an acid radical, diazo-reac'tion, Ehrlich's reaction; a reaction obtained by treating the urine in the manner to be described; tuberculosis. To inch of urine in the test tube are added a, like amount of a saturated solution of pure sulphanilic acid in 5 per cent. hydrochloric acid, and 2 drops of i per cent, solution of sodium nitrate; this is shaken until an abundant froth forms and then a little spirit of ammonia is poured down the side of the tube. A coloration of the froth and sometimes, but le certainly, by a claret color of the subjacent urine.