574 



SCIENCE. 



[N. S. Vol. VIII. No. 200, 



food problem. With the object of burning 

 out nitrogen from air so as to leave argon 

 behind, Lord Eayleigh fitted up apparatus 

 for performing the operation on a largei- 

 scale, and succeeded in efi'ecting the union 

 of 29.4 grams of mixed nitrogen and oxy- 

 gen at an expenditure of one horse-power. 

 Following these figures it would require one 

 Board of Trade unit to form 74 grams of 

 nitrate of soda, and therefore 14,000 units 

 to form one ton. To generate electricity in 

 the ordinary way with steam engines and 

 dynamos, it is now possible, witli a steady 

 load night and day, and engines working at 

 maximum efiRciency, to produce current at 

 a cost of one-third of a penny per Board of 

 Trade unit. At this rate one ton of nitrate of 

 soda would cost 26L But electricity from coal 

 and steam engines is too costly for large in- 

 dustrial purposes ; at Niagara, where water 

 power is used, electricity can be sold at a 

 profit for one-seventeenth of a penny per 

 Board of Trade unit. At this rate nitrate 

 of soda would cost not more than bl. per ton. 

 But the limit of cost is not yet reached, and 

 it must be remembered that the initial data 

 are derived from small-scale experiments, in 

 ■which the object was not economy, but 

 rather to demonstrate the practicability of 

 the combustion method and to utilize it for 

 isolating argon. Even now electric nitrate 

 at 5L a ton compares favorably with Chili 

 nitrate at 11. 10s. a ton, and all experience 

 shows that when the road has been pointed 

 out by a small laboratory experiment the in- 

 dustrial operations that may follow are 

 always conducted at a cost considerably 

 lower than could be anticipated from the 

 laboratory figures. 



Before we decide that electric nitrate is a 

 commercial possibility a final question 

 must be mooted. We are dealing with 

 wholesale figures, and must take care that 

 we are not simply shifting difficulties a little 

 further back without reallj' diminishing 

 them. We start with a shortage of wheat. 



and the natural remedy is to put more land 

 under cultivation. As the land cannot b& 

 stretched, and there is so much of it and na 

 more, tlie object is to render the available 

 area more productive by a dressing with 

 nitrate of soda. But nitrate of soda i& 

 limited iu quantity and will soon be ex- 

 hausted. Human ingenuity can contend 

 even with these apparently hopeless difficul- 

 ties. Nitrate can be produced artificially 

 by the combustion of the atmosphere. Here 

 we come to finality in one direction ; our 

 stores are inexhaustible. But how abotit 

 electricity ? Can we generate enough energy 

 to produce 12,000,000 tons of nitrate of soda 

 annually ? A preliminary calculation shows 

 that there need be no fear on that score;. 

 Niagara alone is capable of supplying the 

 required electric energy without much 

 lessening its mighty flow. 



The luture can take care of itself. The 

 artificial pi-oduction of nitrate is clearly 

 within view, and by its aid the land devoted 

 to wheat can be brought up to the thirty- 

 bush els- per-acre standard. In days to come, 

 when the demand may again overtake sup- 

 ply, we may safely leave our successors to- 

 grapple with the stupendous food problem. 



And, in the next generation, instead of 

 trusting mainly to food-stuffs which flourish 

 in temperate climates, we probably shall 

 trust more and more to the exuberant food- 

 stuffs of the tropics, where, instead of one 

 yearly sober harvest, jeopardized by any 

 shrinkage of the scanty days of summer 

 weather, or of the few steady inches of rain- 

 fall, Natureannuallysupplies heat and water 

 enough to ripen two or three successive 

 crops of food- stuffs in extraordinary abun- 

 dance. To mention one plant alone, Hum- 

 boldt — from what precise statistics I know 

 notr— computed that, acre for acre, the food- 

 productiveness of the banana is 133 times 

 that of wheat ; the unripe banana, before 

 its starch is converted into sugar, is said to 

 make excellent bread. 



