CH. XII.] ACETO-ACETIC ACID. 317 



B. If A is positive shake 50 cc. of urine and 3 drops of strong 

 sulphuric acid with ether. Pipette off the ether and treat it with 

 very dilute ferric chloride. The lower layer becomes coloured 

 violet. Add more ferric chloride. The colour changes to a Bordeaux- 

 red. 



NOTE. It is advisable to shake the acidified urine first with chloroform 

 or benzene, to extract salicylic acid. 



391. Hartley's test for aceto-acetic acid. To 10 cc. of 



urine add 2-5 cc. of concentrated hydrochloric acid and I cc. of a 

 freshly prepared I per cent, solution of sodium nitrite. Shake and 

 allow to stand for two minutes. Now add 15 cc. of strong ammonia, 

 then 5 cc. of a 10 per cent, solution of ferrous sulphate. Shake, 

 pour into a large boiling tube and allow to stand undisturbed. A 

 violet or purple colour slowly develops if aceto-acetic acid be present. 

 The speed at which the colour develops depends on the concentration 

 of aceto-acetic acid. With small amounts the colour may not 

 develop for about 5 hours. The test shows in a dilution of I in 

 50,000. 



Jj. Glycuronic Acid. 



Glycuronic acid, CHO.(CHOH) 4 .COOH, is not found 

 free in the urine. It is found conjugated with certain 

 drugs, or with substances formed from these in the body. 

 These conjugated glycuronates are excreted after ad- 

 ministration of chloral, camphor, naphthol, menthol, 

 phenol, morphine, oil of turpentine, antipyrin, etc. The 

 free and conjugated acids are reducing substances, but 

 are not fermentable. They give the reactions for the 

 pentoses, but can be distinguished by the test given below. 



392. Tollen's test for glycuronates. To 5 cc. of the urine 

 in a rather wide test-tube add -5 to i cc. of a I per cent, solution of 

 naphthoresorcin in alcohol and 5 to 6 cc. of strong hydrochloric acid. 

 Heat slowly to boiling point and keep boiling for i minute, shaking 

 the tube the whole time. Set the tube aside for 4 minutes, then 

 cool under the tap and shake with an equal volume of ether. The 

 ether is coloured violet to red, and when examined spectroscopically 

 shows two bands, one on the D line, and one to the right of it. 



