The Groundwork of the Universe, 8cc. 79 



atmospheric nitrogen is combined with hydrogen to yield ammonia. 

 The difficulty arising in this process is due to the dual action of 

 heat upon the combination. At ordinary temperatures nitrogen 

 has no affinity for hydrogen, while if the temperature is too high 

 any ammonia formed is quickly decomposed. To meet this 

 difficulty the inventors used a catalyst, which allowed of com- 

 bination even at a comparatively low temperature under pressure. 



By these various methods then the problem has been solved, 

 and the nitrogen supply of the world rendered secure. 



During the war there was a great advance in the actual 

 production of nitrogen compounds by chemical methods. The 

 necessity of a large supply of nitrogen compounds for the manu- 

 facture of explosives caused the expansion of the plant in use, 

 and this will remain as a means of production for the manufacture 

 of fertilisers, now that the demand for explosives has so greatly 

 lessened. 



With regard to the synthetic production of food materials 

 themselves, it must be admitted that such production has hardly 

 yet emerged from the experimental stage. The progress, however, 

 which has been made in synthesising extremely complicated 

 materials akin to the proteins has been very marked during the 

 last decade. Even greater progress has been made in the present 

 generation in the laboratory production of different sugars which 

 occur in nature, such as glucose, cane-sugar, milk-sugar and fruits- 

 sugar. The chemist is even synthesising certain sugars which do 

 not occur naturally at all, though the possibility of their occurrence 

 could be seen on theoretical grounds. 



When we seek the origin of the power we use, we find that 

 the greater part comes to us from the sun. Our coal is yielding 

 up to us the heat stored up in it by the sun long ages ago. Our 

 water powers are due to the present action of the sun's rays, 

 and the only fuel not certainly owing its energy to the sun is 

 mineral oil. 



It seems possil)le that, during the volcanic age of the earth's 

 history, certain carbides were produced by the combined heat 



