394 Mixter — Heat of Formation of Titanium Dioxide. 



Heat effect.. 14,8S9 C 14,7Y0 C 



" of oxidation of sulphur. —5,27 l c —5,271° 



" " " " iron 6 — 48° 6 — 48 c 



" " oxygen absorbed — 7l c — 70° 



9,499 c 9,381° 



For 1 gram of titanium 4,749 c 4,693° 



The mean is 4,721° and for 48*1 grams of titanium it is 

 227,100°. The temperature of the fusion was above the melt- 

 ing point of silver and no metallic titanium remained. The 

 fusion, when treated with water, left a white residue which 

 dissolved on addition of an excess of hydrochloric acid and the 

 solution had the red color of pertitanic acid. 



Titanic Oxide. 



Titanic oxide was prepared as follows : The hydroxide, 

 purchased for the pure compound, was fused with potassium 

 pyrosulphate, the fusion was dissolved in cold water and the 

 titanic acid was precipitated by boiling. It was washed with hot 

 water, digested with hot ammonia and washed again and 

 finally heated to redness for an hour. It contained no iron, 

 alumina or zirconia. The following are the experimental data : 



3 4 5 



Titanic oxide 3*302 gr. 4-001 gr. 3*970 gr. 



" " in residue, __ 0*057 " 0*074 " 0*103 " 



" " combined _.. 3*245 " 3*927 " 3*867 " 



Sulphur 1*000 " 1*000 " 1*000 " 



Sodium peroxide 16 " 18 " 19 " 



Water equivalent of system 3,081 "2,956 " 3,022 " 



Temperature interval 2*417° 2*580° 2*536° 



Heat effect 7,446° 7,626° 7,664° 



" of oxidation of sulph'r —5,271° —5,271° —5,277° 



" " " " iron.. —48° —48° —48° 



" " oxygen evolved. __ +78° +72° 



2,127° 2,385° 2,417° 



For 1 gram of titanic oxide 655° 607° 625° 



The mean is 629° and for 80 grains of titanic oxide it is 

 50,300°. The solutions of the fusions in hydrochloric acid had 

 the red color of pertitanic acid. 



Since a pertitanate is formed when titanium or its dioxide is 

 fused with an excess of sodium peroxide, it is probable that the 



