134 CHEMICAL FERTILIZERS 



the large demand for sulphuric acid in the manufacture of 

 explosives, the supply has become plentiful, and now the 

 problem is to use it all. In 1915 it was suggested that 

 nitre cake or acid sodium sulphate could replace sulphuric 

 acid in the manufacture of superphosphate and also partly 

 replace that used for absorbing ammonia in the production 

 of sulphate of ammonia. 



During the war arrangements have been made in this 

 country to bring over Australian zinc ores, which had for- 

 merly gone to continental works where they were convex ted 

 into metal and sulphuric acid. The utilization of such 

 sulphuric acid in this country will depend largely upon the 

 development of the superphosphate industry. Opinions 

 given by Sir Thomas Middleton and Sir Charles Fielding are 

 in agreement as to the use of superphosphate becoming 

 increasingly necessary in the future. As is natural in the 

 case of such attempts to read the future, the figures are 

 somewhat wide apart, but the lesson is the same. Tke 

 available supply of basic slag shows little likelihood of 

 reaching the amount required, and the manufacture of 

 superphosphate or other phosphatic fertilizers must be 

 increased accordingly. The extension of the export trade 

 is a difficult problem, but perhaps Australia, South Africa 

 and India will require quantities of phosphatic fertilizers, 

 although they will doubtless make some of the necessary 

 superphosphate. In Great Britain the future development 

 of the fertilizer trade may be closely connected with the 

 establishment of the zinc industry upon a sound economic 

 basis. For the latter purpose it is essential that the works 

 be situated in the neighbourhood of deep-water ports. Zinc 

 sulphide is ill adapted to compete with pyrites as a source 

 of sulphuric acid, but as sulphur dioxide must be produced 

 in making zinc, it is only a question of bookkeeping to decide 

 which item should be credited with the profit. The Avon- 

 mouth zinc sulphur plant alone was estimated to produce 

 200,000 tons of superphosphate per annum, and, should these 

 works ultimately succeed and be extended, the position of 

 the superphosphate industry would be vety vitally affected. 



