66 HANDBOOK FOR BIO-CHEMICAL LABORATORY. 



ALMEN'S Reaction (Blood). Mix in a test-tube equal vol- 

 umes of tincture of guaiacum and old turpentine which lias 

 become strongly ozonized by the action of air under the in- 

 fluence of light. Allow the liquid to be tested to flow down 

 gently on the surface of this mixture. If blood or blood - 

 coloring matters are present, a bluish-green and then a beau- 

 tiful blue ring appears where the two liquids come together, 

 and if shaken the liquid becomes more or less blue. Pus 

 gives a blue color with this mixture, but in this case the tinct- 

 ure of guaiacum alone, without turpentine, is colored blue. 



ALMEN'S Test (Glucose). Heat liquid with a solution of 

 bismuth subnitrate dissolved in caustic soda and Rochelle 

 salts. If glucose is present, the liquid becomes dark, 

 cloudy, dark brown, or nearly black, and non-transparent. 

 After a time a black deposit appears. 



ANDREASCH'S Eeaction ( Cystein). Treat the hydrochloric 

 acid solution with a few drops dilute ferric chloride solution 

 and then ammonia. The liquid will become beautifully red, 

 darkening on shaking with air. 



AXENFELD'S Test (Albumin in Urine). Acidify with formic 

 acid and add, drop by drop, a 0.1 per cent gold chloride solu- 

 tion and warm. The solution becomes first red, then purple 

 red, and, on the further addition of gold chloride, blue, and 

 lastly, a blue precipitate is produced. The red coloration is 

 characteristic of albumin, while the blue and violet may be 

 produced by other bodies, such as glucose, glycogen, starch, 

 leucin, tyrosin, uric acid, urea, creatinin, etc. 



BAEYER'S Reaction (Glucose). On boiling a glucose solu- 

 tion with ortho-nitrophenyl propiolic acid and sodium carbo- 

 nate indigo is formed. With an excess of glucose this blue, 

 is converted into indigo white, 



