342 MATERIAL BESOURCES OF LIFE. 



Eight here it comes to mind that uncombined nitrogen forms over three- 

 fourths of the weight of the air — a provision of about eleven pounds on 

 every horizontal square inch — and a question rises, "Why cannot the vital 

 forces take hold on the pure element and use freely from its most lavish 

 supply?" Well, because the universe exists. The stomach does not digest 

 the carbon of charcoal; nor do the lungs take oxygen from water. To pro- 

 pose any alteration in the character of one of the sixty-three elements is to 

 undertake the reconstruction of the universe. It is the character of ni- 

 trogen to refuse chemical combinations, Uncombined nitrogen is nowhere 

 available for vital uses, to any appreciable extent. Pilling perfectly its 

 humble service in Nature as a diluent in the air, its qualification is to be 

 inert and to remain changeless. Among the resources of life and in the 

 marts of subsistence where its compounds rank high in value, nitrogen as 

 a simple has no place at all. 



This barrier between nitrogen and its compounds seems to hold firm 

 from age to age. Out of the ocean of atmospheric nitrogen the plant selects 

 the scattering molecules of nitrogen compounds and elaborates therefrom 

 many nitrogenous substances. The animal elaborates some of these into 

 other compounds. But in the final decay of products and tissues, and food 

 not assimilated, the nitrogen of all returns again to ammonia — again in the 

 aerial ocean, and again the resource of plants. If ammonia is oxidized in 

 the air to nitric acid, the latter is deoxidized in the soil to nitrous acid and 

 then to ammonia. All these compounds are very frail, and change most 

 constantly, but together they hold the little stock of united nitrogen, losing 

 little of it and gaining little for it, from epoch to epoch. 



There are leakages, to and fro through this remarkable barrier, it is true, 

 but they are so small that little is known of them, except that they show 

 the strength of the barrier that limits them. On the one side, there is a 

 little loss, by the liberation of traces of nitrogen in its certain organic 

 decompositions. Also, the explosive agents used by man in warfare and 

 the arts result in the liberation of nitrogen — an expenditure of life-resources- 

 On the other side, by the electrical disturbances of the atmosphere, traces 

 of nitrogen are brought into union. The roll of thunder indicates the 

 restoration of a modicum of that good material which was wasted for the 

 roll of artillery. Again, it is believed that in organic decay under re- 

 stricted conditions some measure ot nitrogen is brought into union with 

 nascent hydrogen 



Chemical art has not done anything toward the appropriation of this 

 obstinate element. Nothing nitrogenous can be made of nitrogen. The 

 manufacturers depend on gatherings from the sparingly distributed nitrates 

 of the earth. As machinists have dreamed of perpetual motion, sleeping 

 chemists may dream of an invention to bring atmospheric nitrogen into use, 

 that all the barren places may be made fertile, and the whole earth flourish 

 as a garden of fatness. But for this dream to realize the proportions of a 

 fair probability it is quite essential that chemistry should be well asleep. 



