96 The Phosphates of America. 



for lump pyrites and about 40 feet for " smalls," and an external 

 diameter of 10 feet square, its foundation must be solid and its outer 

 framework offer no impediment to a free circulation of the air. 

 A very good form is shown in the accompanying illustration, and 



SECTIONAL VIEWS OF THE ''GLOVER" OR DENITRATING TOWER. 



its construction is extremely simple. It has a framework of iron, 

 lined throughout with twelve-pound sheet-lead without cross-joints. 

 This is in its turn lined with small glass cubes and pounde^. glass- 

 filling, to a thickness varying from a foot to a foot and a half. The 



