96 THE XITEOGEX PROBLEM. 



et-oiioiuic study. The early stages of this evolution have been 

 marked by a steady progress, as the pages of onr Journal can 

 prove, but at the commencement of any new work much labour 

 of a routine character is unavoidable. before Ave can place our- 

 selves in the front line with the scientific workers in older 

 countries, happy in the heritage of its accomplishment by those 

 who blazed the trail before them. During this period, whilst 

 we have been setting our house in order, great achievements 

 have been made in science in all its branches, and I shall 

 venture to-night to direct your attention for a brief moment 

 to one of the greatest of these, whether viewed from the 

 academic, commercial or national standpoint, namely, the 

 chemical problem of the fixation of atmospheric nitrogen, the 

 v-uccessful solution of whi(di has already proved of the most 

 profound significance, botli during the r)iping times of peace 

 and in the tempestuous struggles of the late war. 



The Nitrogen Problem. 

 It has long been known to the farming community that 

 in the rotation of crops it was distinctly beneficial to include 

 a leguminous species, but the reason for this procedure was 

 not forthcoming until the researches of AVarington, and later 

 of Winogradsky, had explained the function of the enlarged 

 nodules found on the roots of these plants, namely, the bacterial 

 transmission of aerial nitrogen in compound form to the soil. 

 Again, the physiological chemist divides the foodstuffs which 

 maintain our existence into five well-known classes, one only 

 of these containing the element nitrogen, namely, the proteins. 

 Further, it has been i)roved by numerous experiments that, in 

 the absence of this particular class m a diet, life soon ceases, 

 thus establishing the fact that the element nitrogen is a neces- 

 sity for the maintenance of life. About the middle of last 

 century, Liebig, Lawes, Gilbert and others proved that for the 

 fullness of groAvth plants must be grown on a soil containing a 

 sufficiency of the elements nitrogen, potassium and i^hosphorus 

 in such form as to be easily assimilated by the roots. In virgin 

 soils, such as are to be found in all new countries, these com- 

 pounds exist in greater or less measure, but with cultiA'ation the 

 soil soon becomes exhausted and consequently unfertile. To 

 lemedy this defect with respect to the element nitrog^en, the 

 supijlies of saltpetre found in Chili were utilised, and this 

 substance proved to be excellent for the purpose. In addition 

 to this, the residual nitrogen found in coal, which is obtained 

 in the form of ammonia when this substance is destructively 

 distilled, has been utilised for this purpose since the early 

 'nineties to an increasing extent. 



These two substances, sodium nitrate and ammonium 

 sul])hate, were the only artificial nitrogenous manures available 

 at the beginning of this century. In 1898 the late Sir William 

 Crookes drew the attention of chemists to tlie fact that the 

 available supplies of these two fertilisers were insufficient to 

 meet the demands whi(di would be created by the food require- 

 ments of the expanding population of the world ; at the same 

 time he drew attention to the oceans of free nitrogen present 



