HANDBOOK FOB BIO-CHEMICAL LABORATORY. 83 



LOWENTHAL'S Test (Glucose). On boiling a glucose solution 

 witli a solution of ferric chloride dissolved in tartaric acid and 

 sodium carbonate it darkens and soon deposits a voluminous 

 precipitate of iron oxide. This test cannot be applied to the 

 urine, as all urines give it, 



LUCRE'S Reaction (Hippuric Acid). Evaporate the sub- 

 stance to dryness with nitric acid, when an intense odor of 

 nitro-beuzol (oil of bitter almonds) is generated when the 

 residue is heated. 



NN'S Test (Indican in Urine). Equal parts of urine 

 and hydrochloric acid and a few drops nitric acid are boiled, 

 cooled, and agitated with chloroform. The chloroform is 

 colored violet and shows an absorption-band before D, due to 

 indigo blue, and another after D, due to indigo red. 



MACWILLIAM'S Test (Albumin). Add a concentrated wa- 

 tery solution of salieyl sulphonic acid to the acid-reacting 

 solution, when a cloudiness or precipitate will be formed in 

 the presence of albumin. In the presence of peptones or 

 albumoses the precipitate disappears on boiling, but reap- 

 pears on cooling. 



MALERBA'S Test (Acetone). A solution of dimethylpara- 

 phenylendiamine gives a red coloration with acetone, which 

 gives an absorption spectrum very similar to oxyhaemoglobin. 



MALY'S Test (HCl in Contents of Stomach). Place liquid 

 to be tested in a glass dish and add as much ultramarine to 

 make it just blue. Then cover the dish with a watch-glass 

 after having suspended a piece of leud-paper in the upper 

 part of the dish. On warming the mixture on the water- 

 bath after 15 minutes in the presence of HCl the blue color 

 of the mixture has changed to brown and the lead-paper will 

 have turned dark, due to the development of H,S. 



