EXPERIMENT STATION BULLETINS. 



369 



AMMONIA PRODUCTION IN PEPTONE SOLUTION WITH MINERALS. 



(Relative numbers with untreated soil = 100.) 



After two days, we see all cultures alike excejit the two series with 

 P and KP. These two are ^11% and 36% ahead of the others. The favor- 

 able influence is due to the soluble jjhosphate, since it does not show 

 in tho.se flasks where phosphate and CaCl, were given at the .same time. 

 Those flasks with phosphates without calcium have a heavy scum, those 

 with both i^hosphate and calcium a thin scum and those without any 

 phosphates, no scum. After 3 days, these two cultures are even 47% 

 and 50% ahead of the untreated cultures. After 5 day.s, however, we 

 notice the contrary. The one has develox>ed 10% less ammonia than the 

 untreated, the other 8% less. After 7 days, the difference is the same 

 and after 16 days the diminution is still more pronounced. 



It seems from this and the other results that it is not so much the 

 quantity of the fermentable material (dextrose or i)eijtone, respectively; 



Fig. 17. Ammonia Production in Peptone Solution with and without 



Minerals. 

 47 



