100 SOIL BACTERIOLOGY 



The urea decreases the solidifying properties of gelatin. 

 If agar medium is wanted, take 15 grams to i liter. 



Medium 24 

 Hippuric Acid Solution 



Sodium hippurate (NaC 9 H 8 NO 3 ) 3.0 gm. 



Dibasic potassium phosphate (K 2 HPO 4 ) 0.5 gm. 



Tap-water 1000.0 c.c. 



Medium 25 

 Uric Acid Solution 



Uric acid (C 5 H 4 N4O 3 ) 3.0 gm. 



Dibasic potassium phosphate (K 2 HPO 4 ) 0.5 gm. 



Tap-water 1000.0 c.c. 



Lohnis, F., Landwirtschaftliche-bakteriologisches Praktikum, Berlin, pp. 

 112, 113, 1911. 



NITRIFICATION 



Medium 26 

 Solution for Nitrite Formation 



Ammonium sulphate (NH 4 )2SO 4 i.o gm. 



Dibasic potassium phosphate (K 2 HPO 4 ) i.o gm. 



Magnesium sulphate (MgSO 4 + yH^O) 0.5 gm. 



Sodium chlorid (NaCl) 2.0 gm. 



Ferrous sulphate (FeSO 4 + 7H 2 O) 0.4 gm. 



Magnesium carbonate (MgCOs) in excess about 5.0 gm. 



Distilled water 1000.0 c.c. 



In order to prevent any loss of ammonia, it is well to sterilize 

 the ammonium sulphate separately. A 10 per cent, solu- 

 tion will be found very convenient. When cool, the proper 

 amount of ammonium sulphate may be added with a 

 sterile pipet. 



Winogradsky, Lafar, Technische Mykologie, Bd. 3, pp. 132-181, 1904. 



