144 THE NEW WORLD OF SCIENCE 



in Germany wherein the potassium carbonate, from beet root 

 residues, was made to react in aqueous solution with Chile salt- 

 peter as follows : 



K 2 CO 3 + 2NaNO 3 > Na 2 CO 3 + 2KNO 3 



thus hot only supplying the desired potassium nitrate but also 

 greatly fostering the beet root sugar industry that Germany 

 was then seeking to promote. It was also known that about 

 this time there was discovered in the sinking of a shaft at the 

 Stassfurt salt mines the so-called abraumsalze containing 

 quantities of sylvite or mineral potassium chloride and that 

 at the opening of the Civil War in the United States there was 

 developed a method of producing saltpeter by metathesis of 

 potassium chloride and sodium nitrate in aqueous solution as 

 follows 



KC1 + NaNO 3 -> NaCl + KNO 3 



With these and many other precedents existing it appeared 

 a simple matter to produce ammonium nitrate from the meta- 

 thesis of ammonium sulphate and sodium nitrate in aqueous 

 solution as follows: 



(NH 4 ) 2 SO 4 + 2NaNO 3 > Na 2 SO 4 + 2NH 4 NO 3 



Owing, however, to the possible formation of three different 

 phases of sodium sulphate, five enantiotropic phases of am- 

 monium nitrate, and four different double salts with differing 

 solubilities, the problem was a most complex and intricate one 

 and many who sought to solve it failed. It was solved by 

 Freeth and Cocksedge through a careful quantitative study of 

 the solubility relations and the regulation of the temperature 

 within narrow limits as a result of the information obtained 

 from these data, and their discoveries were protected by Eng- 

 lish Patent 16,454 of 1910. The method was commercially de- 

 veloped during the war at the plant of Brunner-Mond in Eng- 



