The Romance of Modern Chemistry

HIGH TEMPERATURES forming calcium carbide and carbon monoxide; the phosphorus, on the other hand, escapes as a vapour, and is condensed under water in the usual manner. It is not only in the electric furnace that the high temperature of the electric arc has been utilised, but also in connection with the interesting problem of the utilisa- tion of nitrogen from the atmosphere for agricultural purposes. For the fertilisation of the soil large quantities of nitrogenous material are required, which are at present derived to a great extent from Chili, where extensive de- posits of sodium nitrate—Chili saltpetre, as it is called— are found. Those who should know best are of opinion that these nitrate beds will be exhausted in thirty years or thereabout, and hence it was that Sir William Crookes, in his pi’esidential address to the British Association in 1898, insisted on the necessity of discovering some way by which the great store of nitrogen in the atmosphere could be made available. The problem is by no means easily solved, for nitrogen is very slow to enter into combination with other elements. With the aid of the electric arc, however, it is possible to induce some of the oxygen and nitrogen in the air to unite, forming nitric oxide, which in its turn can easily be converted into nitric acid or nitrates. This has been known to chemists for a long time, but it is only recently that the difficulties in the way of making the process a commercial success have been overcome. Within the last few years the necessary plant for carrying out this process on the large scale has been set up in Norway, where power is cheap; the factories there are now turning out large quantities of nitrate of lime, suitable for fertilising purposes, and capable of replacing the natural nitrate brought from Chili. 202