CHEMICAL PROPERTIES OF CLAY 



71 



oxide. No. VII, at the extreme left, represents the fusion point 

 of the clay alone, while I, II, etc., indicate, respectively, the 

 fusion points of the clay and titanium mixtures. From this it 

 will be seen that even one-half per cent, of titanium oxide lowered 

 the fusing point of the clay half a cone, while 5 per cent, lowered 

 it two cones. All the mixtures, when heated to cone 27, were 

 apparently vitrified, and showed a deep-blue fractuira. This 

 coloration was, however, destroyed by the presence of a few per 

 cent, of silica. At lower temperatures (cone 8), a mixture con- 

 taining 5 per cent, of titanium oxide burned yellow. 



Seger 

 Cone /Yaj6 



35 



















yn 











3: 



31 

 31 



*-—- u. 



"^~"~~ ii! 



— ___! 



v 



- — -_i 



1 











\^ 



Kao/i 



n and Titan 1 



um Oxide 

















7.t/t/w/o 



r<3 



M OJT/DEOS 1 2. 3 Or 



2.5. Curve show/ng effect of 77fanium oxide on fus/hrf/fy of clay. 



The effect produced by replacing silica by titanium oxide in 

 a mixture of silica and kaolin is mentioned on another page. 1 



Water in Clay. 



Under this head are included two kinds of water. 1. Me- 

 chanically combined water or moisture. 2. Chemically com- 

 bined water. 



Mechanically combined water. — The mechanically combined 

 water is that which is held in the pores of the clay by capillary 



1 Chapter XVI, Fire Clays and Fire-Brick Industry. 



