ElvISHA MITCHELL SCIENTIFIC SOCIETY. 21 



trites were formed and they were noticed always to 

 precede the formation of nitrates. This led Waring- 

 ton to suspect the presence of two different oro^anisms. 

 And various attempts were made to isolate them. 



The Pranklands (P. P. and Grace C; Chem. News, 

 March 21 , 1890) were unable to isolate them by g-elatin 

 cultures. The organisms either did not grow on gela- 

 tin or, when so grown, lost the power of producing ni- 

 trates. They finally succeeded in getting an attenua- 

 tion, one millionth of the original solution, by means of 

 the dilution method, which produced nitrates in suita- 

 ble solutions and had the microscopic appearance of 

 bacilli. Warington (J. Chem. Soc. 1891, 484) finally 

 succeeded in isolating the two organisms, the presence 

 of which was indicated by his previous experiments. 

 Thev are very similar in appearance and belong to the 

 same famil}^ The nitrous organism, isolated through 

 successive cultures in ammoniacal solutions made per- 

 manently alkaline with sodium carbonate, and contain- 

 ing phosphates, oxidized ammonia to nitrous acid only; 

 it produced nitrous acid in solution of milk, urine and 

 asparagine, and could apparently assimilate carbon 

 from acid carbonates. The nitric ferment did not pro- 

 duce either nitrites or nitrates from ammoniacal solu- 

 tions, in fact ammonia hinders its action. It rapidly 

 changes nitrites to nitrates. 



Previous experiments of Warington (J. Chem. Soc. 

 1884, 637) had shown that in all experiments in which 

 nitrogenous organic compounds were used, the forma- 

 tion of ammonia preceded that of nitrites and nitrates. 



Warington believed that ammonia was the only nitri- 

 fiable substance, and only such substances as were 

 capable of forming ammonia through the action of soil 

 organisms could form nitrates. More recent investi- 



