114 SOIL BACTERIOLOGY 



crushed ice. Transfer to a filter and wash until all traces of the acid are 

 removed. When the volume of the nitrate is reduced to about 200 c.c., 

 punch a hole in the filter; wash filtrate into a flask. Make volume up to 

 800 c.c. 



Scales, F. M., Centbl. Bakt. (etc.), Abt. 2, Bd. 44, p. 661, 1915. 



Medium 53 

 Cellulose Agar 



(a) Agar 10 gm. 



Dibasic potassium phosphate (K 2 HPO4) i gm. 



Magnesium sulphate (MgSC>4 + 7H 2 O) i gm. 



Sodium chlorid (NaCl) i gm. 



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



Calcium carbonate (CaCOs) 2 gm. 



Tap-water 500 c.c. 



(6) Cellulose solution 500 c.c. 



1. Pour 1000 c.c. of ammonium hydroxid, sp. gr. 0.90, 

 into a glass-stoppered bottle; add 250 c.c. of distilled water 

 and 75 grams of pure copper carbonate; shake the solution 

 vigorously until all the copper is dissolved. (About ten 

 to fifteen minutes are ordinarily required.) 



2. To the copper-ammonium solution add 15 grams of 

 high-grade sheet filter-paper; shake vigorously at intervals 

 of ten minutes for one-half hour. Examine the solution 

 carefully to see that the paper is completely dissolved. 

 If any particles of paper remain in the solution, the shaking 

 must be continued until the solution is perfectly clear. 

 Dilute 250 c.c. of the amonium-copper-cellulose solution 

 to 10 liters with tap-water; add slowly, with frequent 

 shaking, a weak hydrochloric acid solution prepared by 

 adding 500 c.c. of concentrated acid to 10 liters of tap- 

 water. Continue the addition of the acid until the blue 



