All About Inventions and Discoveries
The Romance of modern scientific and mechanical Achievements

Living on the Air 263 ever, is an inert gas, and will not readily combine with any other element. When Cavendish observed the phenomena occurring from the combustion of hydrogen in free air by means of the electric spark, the question that faced him was : What becomes of the nitrogen? He pursued his investigations to determine this point, and a few years after his discovery of hydrogen he found that at the same time as the combination of the hydrogen and the oxygen formed water, the inert nitrogen became oxidised, and that when this nitric oxide, as it is called, came into contact with the water formed by the combination of the hydrogen and the oxygen, it produced nitric acid. The experiment carried out by Cavendish excited scientific circles, but, strange to say, it was not followed up, except in a desultory manner. It was regarded purely and simply as an illuminating labora- tory demonstration. No one conceived the idea that the discovery might be commercialised and be developed into an important industry. That was 150 years ago. To-day, what Caven- dish produced in his laboratory upon a small scale is being practised upon a huge basis, and, what is more, is being developed with striking rapidity. What has been the reason for this sudden and feverish interest in what was originally considered to be merely a fascinating experiment ? The reply is readily forth- coming—to save the world from starvation ! Nitrogen is not only indispensable to the mainten- ance of our existence. It is equally vital to plant life, though in varying degree. But the vegetable kingdom cannot, so far as we know, absorb the in-