1915] on Science and Industrial Problems 311 



case with so many brilliant discoveries of English scientists, no 

 practical use has been made of it in this country, and though its 

 development into an industry has been partly due to the cheap water 

 power obtainable in Norway, the determining factors have been the 

 indomitable skill and perseverance of Norwegian physicists, chemists, 

 and engineers. 



Lord Rayleigh showed that electric sparks would cause the union 

 of nitrogen and oxygen with the formation of nitric oxide ; but it 

 was the Norwegian physicist, Birkeland, in conjunction with his 

 countryman the engineer Eyde, who, by the gradual development of 

 laboratory experiments, were first able to demonstrate that furnaces 

 could be built capable of dealing with from 700,000 to 800,000 litres 

 of air per minute. As the air after passing through the furnaces 

 contains little more than one per cent of nitric oxide, the problem of 

 oxidizing this gas and absorbing the resulting nitrogen peroxide is a 

 very difficult one ; for the more dilute the gas, the more difficult the 

 opeVation. But organized research proved irresistible, and now no 

 less than 08 per cent of the nitrogen peroxide is absorbed in a series 

 of five large towers by either water or sodium carbonate solution, 

 giving rise to a mixture of nitrous and nitric acids. The separation 

 of these two substances required the intervention of yet another type 

 of experimenter, namely, the physical chemist, or one who especially 

 studies the ground which cannot be allotted strictly to either physics 

 or chemistry, but is common to both. 



It was found that with increasing concentration nitrous acid be- 

 comes more and more unstable in aqueous solution, so that a further 

 process takes place, resulting in the formation of more nitric acid 

 and nitric oxide : — 



3HN0, = 2N0 + HNO3 + H,0 



and, under certain conditions of temperature and amount of water 

 present, the instability of nitrous acid becomes so great that only 

 nitric acid is formed, the practical result being that in the first tower 

 not only the strongest nitric acid, but an acid free from nitrous acid 

 is produced. 



The nitric oxide formed as in the above equation is then 

 oxidized, and again absorbed, so that the amount of nitrous acid 

 increases in each succeeding tower, until in the fifth tower, where 

 sodium carbonate solution is used as the absorbent, nearly pure 

 sodium nitrite is produced. 



These are some of the main points which have been overcome by 

 the joint and organized eiforts of many men. There may be added 

 the difficulties of a physical-geographical, and engineering nature, 

 which had to be surmounted in order to bring imder complete 

 control a waterfall with a perpendicular drop of over 500 feet : to 

 dam a mountain lake so as to transform it into a reservoir holding 

 840 million tons of water, capable of generating continuously in 1,he 



