10 LVBOEATOfiT BACTERIOLOGY. 



TRANSFORMATION OF NITROGEN COMPOUNDS. 

 GROUP I. AMMONIFICATION. 



Exercises IV. to XVII. 



EXEECISE IV. 



AMMONIFICATION IN PEPTONE SOLUTIONS. 



1. Make up a 1% solution of Witte's peptone in water. 



2. Measure out six 100 cc. portions into 500 cc. Jena 

 flasks. 



-3. Plug and sterilize in the autoclave at 15 lbs. pressure 

 for 10 minutes. 



4. Prepare a soil infusion of each of the three soils to be 

 examined, by shaking 100 grams in 200 cc. of sterile water 

 for 5 minutes. 



5. Inoculate the peptone solutions in duplicate with 30 

 cc. (= 10 grams soil) of the various infusions, transferring 

 by means of sterile ]3ipettes. 



6. Incubate for 3 days at 20° C. 



7. At the end of that time, remove the plugs, add about 

 100 cc. of water, 9-10 grams of heavy magnesium oxid, 

 and a small piece of paraffin. 



8. Distil off the ammonia present, collecting it in stand- 

 ard HC'l and titrating against standard NH^OH in ihe 

 usual way. 



