344 THE POPULAR SCIENCE MONTHLY. 



proved by feeding the roots of the plant with additional nitrogen 

 compounds. On all but the richest soils, the suitable application of 

 ammonia or nitrates causes a notable increase in the quantity of food- 

 plants, and also causes au increased proportion of the nitrogenous 

 constituents of plants. If nitrogen compounds could be laid down 

 cheaply enough, it would augment the supplies of food and raiment, 

 and the comfort of man, in no small degree. 



Right here it comes to mind that uncombined nitrogen forms ovej- 

 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 propose 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 nitrogen to refuse chemical 

 combinations. Uncombined nitrogen is nowhere available for vital 

 uses, to any appreciable extent. Filling 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 Avhere 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 elab- 

 orates 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 tlie strength of the barrier that limits them. On the one 

 side, there is a little loss, by the liberation of traces of nitrogen in 

 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. Tlie roll of thunder indicates the restoration of a modicum of 

 that good material which was Avasted for the roll of artillery. Again, 

 it is believed that in organic decay under restricted conditions some 

 measure of nitrogen is brought into union with nascent hydrogen. 



