president's address. 221 



merest traces of nitrous acid appearing. It is interesting to 

 know that the discovery and isolation of the former of these 

 two organisms thns discovered had been, with much care and 

 by long effort, isolated, identified, and published a month before 

 Winogradsky's earlier paper appeared, by Professor Percy F. 

 Frankland, F.R.S., and he has pointed out the full details of 

 the subject.* 



It has long been admitted that one of the most essential 

 sources of nutrition found by plants in the soil is nitric acid. 

 The agriculturist could grow no crops without this, however 

 otherwise complete the soils might be. 



Still it is found on analysis to be most minutely present even 

 in ordinary fertile soils. This arises from its eager consump- 

 tion, when present, by plants, and its being washed out by 

 rains. But the soil under ordinary circumstances constantly 

 generates nitric acid from the many nitrogenous manures placed 

 upon it, and it is in the form of nitric acid that the nitrogen of 

 manures obtains access to plants. This was proved sixteen 

 years ago by showing that the nitrifying process — the produc- 

 tion of nitric acid in the soil — is stopped by all those materials 

 known as antiseptics, as well as by heat and other agencies 

 inimical to life. 



Later it was shown that the process of nitrification could 

 take place in solutions destitute of organic matter. 



In 1886 Professor Frankland and Mrs. Frankland employed 

 this method, in order, if possible, to isolate this special organism, 

 and they carried on a process of nitrification over a period of 

 more than four years, without the organism itself being sup- 

 plied with any organic food. But they succeeded, as Winograd- 

 sky did, in separating a nitrifying organism, but only one 

 which had the property of converting ammonia into nitrous and 

 not into nitric acid. 



Of course the change from ammonia into nitrous acid is as a 

 result in organic chemistry much more difficult to accomplish 

 than the change from nitrous acid into nitric acid. So then 

 the vital process of oxidation must be quite distinct from that 

 effected by purely chemical agents. 



In the later researches of Winogradsky, to which we have 



* Friday evening discourse at the Royal Institution, February 19th, 

 1892, •' Nature," Vol. xlvi, p. 135, et seq. 



JouRN. Q. M. C, Series II., No. 32. 16 



