i'llli CHEMISTRY OF THE SOU-. 79 



The text-books tell us that nitrogen is the most inert of elements. It 

 would, however, be fairer to say that it is characterised by a highly aristo- 

 cratic exclusiveness. So strongly marked is this characteristic, that even 

 when it has been coaxed into certain combinations (such as nitro-glycerine, 

 picric acid, nitrogen chloride, &c), it sets itself free on the slightest provo- 

 cation, and with explosive violence. On account of this aloofness, it has 

 only recently been possible to devise means whereby atmospheric nitrogen 

 can be made to combine in such a form as to be available for plant-food when 

 applied to the soil. Recently, however, experiments have been carried out in 

 several directions which contain considerable promise of success, and the 

 future developments of these processes will be watched with extreme interest. 



Calcium Cyanamide. 



When air from which the oxygen has been removed, and which is 

 practically pure nitrogen, is passed over calcium carbide at a white 

 heat, it combines, forming a compound known as calcium cyanamide, 

 OaCN,, in the form of a fine black powder. This is readily converted by 

 water into ammonia, and the crude cyanamide has been found to possess 

 manurial value, due, no doubt, to the production of ammonia. The results 

 of trials with it at Rothamsted and several of the German experiment 

 stations show that while it has a distinct manurial value, there is nothing to 

 show that it has a higher manurial value than sulphate of ammonia, with 

 which it cannot compete in price, at least at present. There are certain 

 disadvantages connected with its use; for instance, it must not be used as a 

 top-dressing, as loss of ammonia results; nor must it be mixed with super- 

 phosphate, as the mixture becomes hot. It is most efficient when sown about ten 

 days before the seed, as when sown with the seed it has a markedly injurious 

 effect upon the germinating power. It is most effective when mixed with 

 peat, or applied to peaty soils, the peat no doubt acting as an absorbent for 

 the ammonia. It may be said that its future success depends upon whether 

 it can be produced at a cost which will enable it to compete with ammonium 

 •sulphate or nitrate of soda. 



Production of Nitrogen by Electricity. 



Another, and apparently more promising, method of utilising atmos- 

 pheric nitrogen, has been rendered possible by later developments in 

 -electricity. When air is sparked, the nitrogen and oxygen combine to form 

 nitric oxide, which in the presence of water becomes nitric acid. This 

 happens always in the neighbourhood of electrical machines, and the light- 

 ning flashes during thunderstorms also produce the same result, so that the 

 air during thunderstorms always contains small quantities of nitric acid. 

 Many attempts have been made to utilise this action on the manufacturing 

 scale. Amongst the earliest of these which had any measure of practical 

 success was Bradley and Lovejoy's, which was in operation at Niagara Falls 

 until 1904. One of the most successful of these processes is that patented 

 by Birkland and Eyde in 1903 (see Journal of Society of Chemical Investi- 

 gation, 1905). This is being carried out at Savelgfors, in Norway, where 

 works have been erected utilising 30,000 horse-power and producing large 

 quantities of calcium nitrate for use as a manure. The several features of 

 the process are the following: — Air is led into a specially-constructed electric 

 furnace, where it is heated to a very high temperature by an electric arc, 

 spread out into a fan-shape under the influence of powerful electro-magnets. 

 The oxides of nitrosren formed are passed into towers, where they are dis- 

 solved in water and concentrated. The whole of the gases are not, how- 



