138 PRACTICAL PHYSIOLOGY. [XXL 



by the contact method ('/.)• Tlie presence of albumin is indicated by a white 

 deposit in the form of a ring at the line of junction of the fluids. A solution 

 of platino potiissium cyanide may be used instead of the ferrocyanide. The 

 solution of the former is colourless. This test precipitates serum-albumin, 

 globulin, albumose, but not peptone. 



( f.) Picric Acid. — Use a saturated watery solution, and apply it 

 by the contact method of Heller ('•.). The urine is below, and the 

 picric acid on the top. A rapidly-formed deposit at the line of 

 junction of the fluids indicates the presence of a proteid ; the 

 deposit is not dissolved by heat. 



N.B. — Picric acid precipitates all the forms of proteid which occur in urine. 

 It also precipitates mucin, but in this case the deposit usually forms slowly 

 and after a time. If a person be taking quinine, a haziness is obtained in the 

 urine on adding piciic acid, but it disappears on heating. Dr. Johnson and 

 Professor Grainger Stewart recommend it as one of the most reliable tests for 

 albumin we possess, 



((/. ) Metaphosphoric Acid completely precipitates albumin, but it must be 

 freshly prepared, and is diflBcult to keep. Hence it is not satisfactory. 



(h.) Acidulated Brine, as suggested by Roberts, consisting of a saturated 

 solution of sodium chloride with 5 per cent, of dilute hydrochloric acid (B.P.), 

 may be used, but it sometimes gives a precipitate with normal urine. Nor is 

 potassio-mercuric-iodide satisfactory ( Tauret). In cases of doubt, use several 

 tests, especially 2 (b.), (c), (e.), and (/.). 



(i.) Trichloracetic Acid precipitates albumin iu urine. 



(_;.) Salicyl-Sulphonic Acid gives a white precipitate with proteids, which 

 is soluble on heating in the case of albumose and peptone (Ji* William). 



3. Dry Tests. 



(a.) Use the ferrocyanic pellets introduced by Dr. Pavy. 

 {b.) Use the test-papers — citric acid and ferrocyanide of potassium — intro- 

 duced by Dr. Oliver. 



4. Globulinuria. — Serum-globulin is present in nearly every 

 albuminous urine. It gives the reactions described under 2. 



(rt.) Fill a tall glass with water. Drop the urine into the Avator, 

 and observe if a milkiness is seen in the water, indicating the 

 presence of a globulin. This body is not soluble in pure water, 

 but in weak saline solutions (Lesson I. 6), hence on diluting the 

 urine it is precipitated. 



{h.) Test the urine by the contact method with a saturated solu- 

 tion of magnesic sulphate. 



(c.) 'J his body is completely precipitated on saturating the urine 

 with ammonium sulphate. 



If globulin be present along with serum-albumin add an equal 

 volume of a saturated solution of ammonium sulphate. A white 

 flocculeut precipitate indicates globulin. 



