62 Dr Seller on the Nutrition of Plants. 



it returns again to the state of ammonia. In regard to one 

 great source, at least, of the consumption of nitre, namely, the 

 discharge of gunpowder, it is known that the nitrogen is 

 evolved in the uncombined state ; and is thus, under Liebig's 

 view, irrecoverably lost as a means of sustenance to living 

 bodies. Thus, gunpowder would shew itself under a doubly 

 fatal character; — fatal in its immediate effect on life, and fatal, 

 by tending to abridge the duration of the organic world ! 



But the number of cases now known in which ammonia 

 forms from its elements, makes it impossible to join with 

 Liebig in opinion, that ammonia is not produced from its ele- 

 ments in nature, independently of the presence of organic 

 matter. 



This is an interesting subject, but the time already occu- 

 pied with these observations requires me to be brief. 



It is long since the production of ammonia from its ele- 

 ments began to engage the attention of chemists. Priestley 

 observed the formation of the volatile alkali under some cir- 

 cumstances ; and it is not far from sixty years since Austin 

 presented his paper to the Eoyal Society of London on the 

 formation of volatile alkali. The evidence known to him was 

 sufficient to warrant the conclusion, not merely that nitrogen 

 and hydrogen unite to form ammonia when in the nascent 

 state, but when one only of its elements, namely, hydrogen, 

 is in that state. He refers to the remarkable experiment in 

 which moistened iron filings, in a jar of nitrogen, confined 

 over mercury, produce ammonia ; and concludes that, " when 

 iron rusts in contact with water in the open air, or in the 

 earth, volatile alkali is formed." I am aware that Liebig as- 

 cribes the presence of ammonia in rust of iron to absorption 

 from the atmosphere, and that an experiment made in his 

 laboratory is thought to confirm this inference. But on such 

 a point, common evidence is not to be listened to. When a 

 current of moist air is passed over red-hot charcoal, carbonic 

 acid and ammonia are produced. Mulder has recently added 

 other experiments beai'ing on the same conclusion. Pro- 

 fessor Johnson has put this subject in a clear light, and has 

 succeeded, I think, in shewing the strongest reason for be- 



