146 



PRACTICAL PHYSIOLOGY. 



[XXIIL 



6. Aceto-Acetic Acid is found in certain diabetic urines, but not in all. 



(a.) To the urine add ferric chloride ; a red colour is obtained if this acid 



be present. If there is a 

 deposit of phosphates, filter. 

 The colour disappears on 

 heating. 



If a diabetic urine con- 

 taining aceto-acetic acid be 

 distilled, this acid is de- 

 composed, and aceton is 

 obtained. 



7. Tests for Aceton 

 (C 3 H 6 0). To obtain the 

 aceton, acidulate half a 

 litre of urine with HC1. 

 The distillate will give the 

 following reactions : 



(a.) Lieben's Test To 

 a weak, watery solution of 

 aceton add solution of iodine 

 dissolved with the aid of 

 potassic iodide, and then 

 caustic soda. A yellow 

 precipitate of iodoform is 

 obtained. The precipitate 

 is generally described as 

 forming hexagonal plates or 

 radiate stars, but I have 

 generally found it to be 

 amorphous or granular. 

 Other substances give the 

 iodoform reaction. 



(b.) Smell the peculiar 

 ethereal odour of aceton. 



(c.) Legal's Test. Add 

 caustic soda solution, and 

 then a solution of freshly- 

 prepared sodium nitro- 

 ;prusside and acetic acid = a 

 'red colour. 



In all cases employ both 

 tests, but they only give a 

 decided reaction in urine 

 when the aceton is in con- 

 siderable amount. To be 



quite certain that aceton is present, a considerable amount of the urine 

 must be distilled, and the tests applied to the distillate. 



8. Tests for Phenol. The method of obtaining phenol from its compound 

 in the urine is given at p. 134. To a watery solution of phenol 



(a. ) Add ferric chloride = a bluish-violet colour. 



(b.) Add bromine water = a yellow (or rather white) precipitate of bromine 

 compounds. 



(c.) Add Millon's reagent = a beautiful red colour or deposit. This reaction 

 is aided by heat. 



FIG. 74. Sacchar-Ureameter, made by Messrs. Gibbs, 

 Cuxsori & Co., Wednesbury. 



