3 2 URINE. [CH. XII. 



this temperature the melt becomes red and is decomposed 

 into benzoic acid, benzonitrile and prussic acid. It is 

 soluble in hot water, alcohol and ethyl acetate : insoluble 

 in benzene and petroleum ether : only slightly soluble in 

 cold water, alcohol, ether and chloroform. It forms an 

 insoluble ferric salt. By hot acids or alkalies it is hydro- 

 lysed to benzoic acid and glycine. When evaporated with 

 strong nitric acid, nitrobenzene is formed. 



364. Isolation from urine by Roaf's method. 500 cc. of 



the urine of a horse or cow are treated with 125 grams, of ammonium 

 sulphate and 7-5 cc. of concentrated sulphuric acid. On standing 

 for 24 hours the hippuric acid crystallises out. Filter off the 

 crystals, and wash with a little cold water. Dissolve in a small 

 amount of hot water, boil with a little adsorbent charcoal, filter, 

 concentrate if necessary, and allow to stand for 24 hours. 



365. To a little hippuric acid in a small evaporating dish add 

 I to 2 cc. of concentrated nitric acid and evaporate to dryness in 

 a water-bath in the fume chamber. Transfer the residue to a dry 

 test-tube, apply heat, and note the odour of nitrobenzene (artificial 

 oil of bitter almonds). 



366. Neutralise a solution of hippuric acid with dilute caustic 

 soda. Add a few drops of ferric chloride. A cream-coloured 

 precipitate of the ferric salt of hippuric acid is formed. 



K. Certain Constituents of Abnormal Urine. 



I. Albumin and Globulin. 



"Albuminuria" is the name given to the condition in 

 which a heat-coagulable protein is found in the urine, no 

 matter whether the protein present is albumin or globulin. 

 As a rule both proteins are present, but albumin is gener- 

 ally greatly in excess of the globulin. 



Albuminuria can be renal ("true") or accidental 

 ("false"). Renal albuminuria can be brought about by an 

 alteration in the blood pressure in the kidney, by a change 

 in the composition of the blood, or by an alteration in the 



