Diazo-

(di-az/-o) [dig, two; azotum, nitrogen]. A prefix signifying that a compound contains phenyl, C6H5, united with a radicle consisting of two nitrogen atoms. D. -reaction or test, a urinary test, valuable in the. diagnosis of enteric fever. The solutions required are (a) a saturated solution of sulphanilic acid, in a 5 per cent, solution of hydrochloric acid; (b) a yz per cent, solution of sodium nitrite. Mix a and b in the proportion of40 c.c. of a to I c.c. of b, and to a few cubic centimeters add an equal volume of urine, and, after shaking well, allow a few drops of ammonia to flow down the side of the tube. A garnet-red color at the point of contact denotes the reaction, or a rose-pink foam after shaking. 227