FOOD FROM THE AIR.

Nelson Evening Mail, Volume XLIII, Issue XLIII, 27 July 1909, Page 1

FOOD FROM THE AIR.

■ MIRACLES OF CHEMISTS" CON- | GRESS.

THE NEW CROP FEEDER. I LONDON, June sth. At the International Congress on Applied Chemistry appeared on Saturday, Professor Berntnsen, director of the Baden Aniline and Soda Factory and one of the greatest authorities on aniline dyes, who gave an illustration of a method, invented in 1905 by Professor Otto Schonherr, for the manufacture of air saltpetre, the manure of the future for our food crops. The lecture was announced for midday, but the large demonstration theatre of" the Central Technical' College was ! so crowded with' delegates longf before ! that time that Professor Armstrong, I who was chairman, asked .Professor ; Bernthsen to begin his lecture' at 11.45. The professor, a tall, bearded man, faced an audience such as is seldom- to be seen. All the seats were taken, 'and delegates crowded everywhere, even on to the platform, regardless of tho sign "Danger" which marked the electric, switches, rows of men and women of all European nationalities sat side by side with the eager, alert Japanese da legates. Professor Bernthsen went to the heart of his subject at once. Of all the* things which agriculturists supply to the ground to stimulate the growth of crops, what are called nitrates are the most important. When nitrogen is omitted the yield of oats falls by 89 per cent. The rotation of crops supplies some of the necessary nitrogen to the soil, but much more is required, and this is best supplied fey Chili saltpetre (sodium nitrate). The world's store of saltpetre, it has been estimated, at the present rate of consumption cannot last longer than from 21 to 42 years. Sir William Crookes in 1899 said that the extraction of nitrogen from the air "is one of the greatest, discoveries awaiting the ingenuity of chemists." It was this discovery which Profesor Bevnthsen was describing. . - ' MADE WHILE YOU WAIT. Four-fifths of the air we breathe is composed of nitrogen, but the problem h to make it combine with oxygen to form what are called nitric and nitrous oxides. This is brought about by the agency of great temperatures. Professor Bernthsen turned to his apparatus which two German mechanics and an engineer had erected. It consisted of a long narrow glass tube with a copper spiral running up it At the sides smaller tubes carried runnine water to cool the upper connection of the spiral. From the. top of the tube ran nn iron tube with a stop cock to cainy away the nitrogen oxides. A current is sent through the glass tube, and the compressed air which is sent in at Uie same time carries an arc flame up through the spiral to the other end of the t.ube. The flame makes the nitrogen and oxygen combine, and this if cooled down and carried away. Professor Bernthsen made a sign to an assistant, the current was switched on. another assistant made a connection at the bottom of the tube, and in a few seconds a brilliant bluish flame was mounting up the glass tube. A few seconds later the delegates saw the familiar brown-yellowish colour of nitrous oxide gas appearing in the globes. The appearance was the signal for prolonged applause. The current employed for the demonstration was at a pressure of 5000 volts, and nearly 6-horse power of electrical energy was used. The gas obtained if mixed with limestone, when calcium nitrate or "air saltpetre," is formed. A slightly different method gives calcium nitrate, which, being richer in nitrogen, may, said the professor, become the artificial manure of the future. A GENIAL RIVAL. This method is claimed to be simpler than that of Professor Birkeland, of Chrisfiania, which was worked out with Mr Samuel Eyde. Professor Birkeland, at the end of Professor Bernthsen's lecture, with good-humored persistence gave a fairly complete account of the discovery he and Mr Eyde hac made two years earlier. His system re quires magnets, and does not yield au ranch. Professor Bernthsen hopes that within a few years the annual output of ah saltpetre will roach 100,000 tons.