132 The N.Z. Journal of Science and Technology. [Sept. 
predicted, and it lias been asserted that they will become exhausted in 
1921. According, however, to the report of the Inspector-General of 
Nitrate-grounds to the Chilian Government, the area of the nitrate-bearing 
deposits covers 78,000 square miles. Out of this whole an area of only 
2,270 square miles has been proved, and it is estimated that there is 
enough payable deposit within this proved area to last over two hundred 
years at the present rate of consumption and with the present methods 
of production—which methods, however, are known to be wasteful, whilst 
valuable by-products are thrown away. There is no doubt that in course 
of time improved methods will be introduced by which, in all probability, 
a greater proportion of the nitrate will be extracted, and in which the by¬ 
products will be better utilized. Possibly also the improved methods may 
enable the thinner layers to be worked and so extend the area of payable 
deposits. In view of this there does not appear to be any justification 
for the assertion that the deposits are being rapidly exhausted. A correct 
appreciation of the Chilian nitrate situation is absolutely necessary in order 
to assess the value of any project having for its object the production of 
artificial nitrates, for Chile nitrate is the standard of value for nitrogen, 
and regulates the price of any other compound of nitrogen according to 
its nitrogen content. It absolutely controls the situation as regards nitro¬ 
genous fertilizers, as it may be used in its natural form. It also has an 
important bearing upon other forms of nitrogenous compounds which may 
be derived from the natural form by chemical reaction, though it is at a 
disadvantage in regard to many of them because of the cost of conversion. 
Recovery of Nitrogen from Coal. 
Next to Chile nitrate in importance is the production of ammonium 
sulphate, the world’s production in 1913 being 1,365,000 tons—-approxi¬ 
mately one-half the output of Chile nitrate. Ammonium sulphate is 
obtained as a by-product from gasworks, coke-ovens, and producer-gas 
plants. This production is continually on the increase, due to extensions 
of gas plants and by-product coke-ovens and the introduction of producer- 
gas plants. It is calculated, for instance, that the by-product coke-ovens 
in the United States are now producing at the rate of 200,000 tons of 
ammonium sulphate per year, and that in three years’ time this output will 
be doubled as a result of the increase in the manufacture of coke and the 
abandonment of the older type of coke-ovens in which the by-products 
were lost. This does not take into account increases from gasworks or 
from gas-producer plants, the latter being able, owing to the nature of 
the process, to recover a much greater proportion of ammonia. 
The recovery of ammonia as a by-product from the distillation of coal 
is not always a profitable process, as it has to compete with Chile nitrate 
on the basis of its nitrogen contents. And as the ammonia has to be 
fixed in the form of ammonium sulphate for the market, the cost of 
production depends upon the price of sulphuric acid, and if this cannot 
be obtained at a low rate the cost of producing ammonium sulphate is 
frequently such as to leave a very small margin for profit, if any, and in 
many cases the expense of recovering the ammonia is too great, and the 
liquor is thrown away. 
In order, therefore, to obtain a correct appreciation of the value of a 
plant for the fixation of atmospheric nitrogen it is necessary to have regard 
not only to the Chile nitrate situation, but also the production of ammonia 
as a by-product from the distillation of coal. 
