HANDBOOK FOR BIO-CHEMICAL LABORATORY. 55 



with 1 to 2 c.c. concentrated alcoholic solution of acid-free 

 zinc chloride. After a few days yellow crystals of creatinin 

 zinc chloride separate out ; these are filtered off, washed with 

 alcohol, dissolved in hot water and decomposed by boiling for 

 about half an hour with an excess of freshly precipitated 

 lead oxide or lead carbonate. Filter while hot, decolorize the 

 filtrate by boiling with animal charcoal, filter again, evaporate 

 to dryness, and extract the residue by strong alcohol in the 

 cold, which removes the creatinin. Creatin remains behind 

 undissolved. 



3. Precipitate -J to 1 litre of urine with phospho-tungstic 

 acid and hydrochloric acid, filter, and treat the precipitate 

 with caustic baryta. Filter, and remove the excess of baryta 

 by means of carbon dioxide, and filter again. Evaporate the 

 filtrate to dryness, extract the residue with strong alcohol and 

 evaporate the alcohol, when the creatinin will be obtained 

 impure. It may be purified as above described. 



Properties. Creatinin crystallizes in long, colorless, highly 

 refractive, rnonoclinic prisms, which do not become white 

 with loss of water when heated to 100 C. It dissolves in 

 11.5 parts cold water and 100 parts cold alcohol, though it is 

 more soluble in hot liquids. It is nearly insoluble in ether. 

 Creatinin combines with HC1 and certain metallic salts, form- 

 ing crystalline compounds. Creatinin acts as a reducing 

 agent, reducing Fehling's and Trommer's solutions; also 

 reducing mercuric oxide to metallic mercury, and yielding 

 oxalic acid and methyl guanidin. 



X a n thin Bases. 



HYPOXAXTHIX, C 5 H 4 N 4 0. 

 ADEXIX, C 5 H 6 N 6 . 



GUANIN, C & H 5 N 5 0. 



Preparation, 250 grms. finely chopped beef liver is placed 



