APPENDIX TO URINE 57 r 



/3-Hydroxybutyric Acid. 



It is difficult to prove the presence of /?-hydroxybutyric acid in urine. If 

 a large amount be present, the urine will show laevo-rotation after fermenta- 

 tion of the glucose. Its presence can only be shown with certainty by extrac- 

 tion in the same way as it is estimated (p. 597). 



(2) PROTEIN. 



A. Coagulable Protein. ("Albumin.") 



Most commonly coagulable protein is found and tested for by : 



(1) Heat Coagulation. 



This is best performed by heating after adding to a little of the filtered, 

 urine one-sixth of its volume of saturated sodium chloride. The precipitate 

 which is formed may consist of coagulated protein or earthy phosphates, or 

 both. The precipitate of earthy phosphates dissolves, whilst the coagulated 

 protein separates out in flakes if 2 drops of 33 per cent, acetic acid be added 

 for every 10 c.c. urine. 



(2) Heller's Test. 



Some urine is poured on to the surface of a little concentrated nitric acid 

 in a test tube, taking care that the two solutions do not mix. To prevent 

 this the nitric acid may be saturated with ammonium nitrate. If protein be 

 present, a whitish ring will form at the junction. There may be also a 

 reddish ring due to indigo red and indigo blue. If the urine be concentrated 

 urea nitrate may separate out, but here the precipitate is obviously crystalline. 

 Uric acid may also separate if a large quantity of urates be present. This- 

 can be prevented by diluting before testing with the nitric acid. 



(3) Hydroferrocyanic Acid. 



This test is given under reactions of proteins (p. 369). 



(4) The Colour Reactions cannot be applied directly to urine, but to the. 

 heat coagulum suspended in water. Millon's reagent and the biuret reaction 

 should be tried;* the coagulum in the latter case is dissolved in hot caustic: 

 soda. v 



Characterisation and Separation of a Mixture of Proteins. 



(a) Albumin and Globulin. The globulin is precipitated by half-saturating 

 the urine with ammonium sulphate and filtered off. It is dissolved in 2 per 

 cent, sodium chloride solution. The solution is acidified and heated. 



The albumin in the filtrate is coagulated on acidifying with acetic acid 

 and heating. The protein nature of the precipitates should be confirmed by 

 the colour tests. 



(b) Protease and Coagulable Protein. The solution is saturated with, 

 ammonium sulphate (8 parts to 10 parts urine) and heated for a few seconds, 

 so that the coagulable protein is coagulated. The precipitate is filtered ofT 

 and extracted with alcohol to remove urobilin, which also gives the biuret re- 

 action. It is extracted with boiling water which dissolves the proteose. This- 

 solution is tested with the biuret, xanthoproteic and Millon's reactions. 



(5) Estimation. 



The protein is estimated by Esbach's method (see under proteins, p. 369). 

 The urine must be acidified with acetic acid if it is not acid and diluted till 

 its specific gravity is i -006-1-008. 



