210 THE CANADIAN NATURALIST. [JtHKBy 



faithful restitution to the soil of the ash-constituents removed in 

 the crops. 



Twelve years ago indeed, the leaders of the " nitrogen "' school 

 carried their doctrine so far as to declare ammonia a sufficient 

 '' substitute " for cinereal manures, " Even supposing,'^ said they 

 (writing in 1851) — "even supposing a mineral manure, founded 

 on a knowledge of the ashes of plants, to be still the great desid- 

 eratum, the farmer may rest contented meanwhile that he has in 

 ammonia^ supplied to him by Peruvian guano, by ammoniacal 

 salts, and by other sources, so good a substitute,"* The 

 reporter does not hesitate to condemn the doctrine set up in this 

 passage as one of unjustifiable spoliation. 



Nine years later (in 1861)f the same writers tell the farmer 

 that an ordinary corn-growing soil, taken as one foot deep, culti- 

 vated in the usual way, and annually exporting its whole produce 

 of corn and meat, without restitution of their cinereal constituents^ 

 contains enough phosphoric acid to support this drain for 1000 

 years, enough potash to meet the demand for 2000 years, and 

 enou2:h silica to last for no less than 6000 years. 



The evident tendency of these stupendous figures is to produce 

 the impression that " restitution" to such a reservoir as this would 

 be a mere absurdity. If the available cinereal treasures, lying 

 within twelve inches under the soles of our feet, be really of this 

 dazzling description, a proportionate supply of ammonia, to bring 

 them as fast as possible into activity, may well be put forward as 

 our chief agricultural requirement. 



We are thus brought back to the nitrogen question ; which, in 

 the light of this doctrine of inexhaustibility, acquires a new and 

 incommensurable importance. For, if we can only match our 

 " inexhaustible " cinereals with a similar supply of ammonia, the 

 lamp of Aladdin (so to speak) is at the disposal of mankind^ and 

 the language of Scheherzade is scarcely gorgeous enough to paint 

 the golden future of our happy race. 



To the momentous question thus raised, the prophets of cinereal 

 plenty afi'ord us, by their new mode of computation, the means of 



* ' Oa Agricultural Chemistry, especially,' &c., see the preceding 

 note. 



t'Ott Some Points in Connection with the Exhaustion of Soils.' 

 ' Report of the Brit. Assoc, for the Advancement of Science ' for 1861. 



