Barbital and other barbituric acid derivatives are usually detected by recrystallization (Bachem), and only few chemical tests for their identity have been described. Most of these tests are obviously crude and unsatisfactory, or at least not specific. One cannot test for the presence of barbital with Millon's reagent, Denigès' reagent, phenylhydrazine and sodium nitroprusside, or sulphuric acid and naphthol (Parri). The murexide test of Handorf is likewise not sufficiently specific. Parri, Zwikker, and Bodendorf used cobaltous salts for the detection of barbiturates, but proved neither the specificity of their tests, nor did they attempt to make them sensitive beyond 1 part in 2000. We devised the following test for the determination of barbiturates. We acidulate the unknown solution with hydrochloric acid, and shake with 10 volumes of chloroform in a separatory funnel. Six cc. of the chloroform extract are divided into 3 equal parts, A, B, and C. To A we add 0.05 cc. of a 1% solution of cobalt acetate in absolute methyl alcohol; to B, 0.1 cc.; and to C, 0.2 cc. of the same. This gives no color beyond a dilution of the original color of the cobalt acetate solution. Then to A we add 0.1 cc. of 1% barium hydroxide solution in absolute methyl alcohol; to B we add 0.2 cc., and to C 0.4 cc. of the same. If malonyl urea derivatives are present in the extract, a blue color always appears in A, may appear in B, or even in C, according to the amount of barbiturates contained therein. This step gives us an approximate idea of the concentration of barbiturates in the solution, for we have found that small amounts of barbital react only to small amounts of the reagents.