HANDBOOK FOR BIO-CHEMICAL LABORATORY. 71 



passes to a chestnut or reddish brown and then to a beautiful 

 purple. Gentle heat facilitates the reaction. 



DEXIGES'S Test (Uric Acid}. If uric acid is converted into 

 alloxan by the careful action of nitric acid, and the excess of 

 nitric acid expelled by gentle warming and then treated with 

 a few drops sulphuric acid and also a few drops commercial 

 benzol (containing thiophen),ablue coloration is produced. 



DEXTROSE. See Glucose. 



DIETRICH'S Reaction (Uric Acid). Add a solution of 

 sodium hypochlorite or hypobromite to the uric acid solu- 

 tion, when a red coloration is produced. This coloration 

 disappears on adding caustic alkali. 



DONNE'S Test (Pus). Stir a small piece of caustic potash 

 with the mass to be tested. If pus is present, the mass is con- 

 verted into a slimy tough material. 



DRAGENDORFF'S Test (Bile Pigments). Place a few drops 

 of the urine on an unglazed porcelain surface and when it has 

 been absorbed add a drop or two of nitric acid. Several 

 rings of color will be produced if bile is present, chief 

 amongst these rings being the green ring, which is char- 

 acteristic of bile pigments. 



DRECHSEL'S Test (Bile Acids). Treat the substance with a 

 little cane sugar and a few drops of a mixture of 5 vols. 

 syrupy phosphoric acid and 1 vol. water. Warm on water- 

 bath, when a beautiful red coloration is produced if bile acids 

 are present. 



DUMONTPALLIER'S Test (Bile Pigments). See SMITH'S Test. 



EIJKMAX'S Test (Phenol). Mix the phenol solution with a 

 few drops of an alcoholic solution of nitrous acid ethyl ether 



