NITROGEN FIXATION LOF 



209 



The proceeds obtained from the export duty imposed by the Chile 

 Government amounts to about 40 per cent of that country's yearly 

 revenue. 



The question is often asked: How long will the Chile deposits 

 last? There is quite a difference of opinion in regard to this. It is 

 estimated that the contents of the surveyed areas contained about 

 300,000,000 tons of nitrate of which about 50,000,000 tons have been 

 mined, leaving about 250,000,000 tons untouched. At the present 

 rate of production this would last about 100 years. It is claimed 

 that the unsurveyed areas are some thirty times larger than the 

 surveyed ones, but undoubtedly of a much lower nitrate content, and 

 it is quite safe to assert that the deposits would last another 250 or 

 300 years. On the other hand, it is almost certain that long before 

 that time new artificial nitrogen fixation processes will have been 

 developed, by means of which it will be possible to manufacture 

 nitrogen compounds at a much lower cost than the cost of Chile salt- 

 peter, so that the mining of Chile saltpeter will undoubtedly be very 

 materially curtailed long before these deposits are exhausted. 



BY-PRODUCT AMMONIA 



The by-product coke-oven industry now occupies a vital place 

 for the supply of nitrogen in the form of ammonia. Besides am- 

 monia, the carbonization of the coal in these ovens gives us many 

 other valuable by-products such as benzol, toluol, and napthalene. 



It is interesting to watch how these modern by-product coke plants 

 rapidly supersede the old-fashioned beehive ovens, as may be seen 

 from the foregoing tabulation. 



A by-product coke oven is a rather complicated structure, but 

 briefly it consists of a large number of parallel chambers or ovens in 

 which the bituminous coal is heated out of contact with the air. 



