H. E. Merwin — Per oxidized Titanium Solutions. 119 



Art. XIV. — Coloration in Per oxidized Titanium Solutions, 

 with Special Reference to the Colorimctric Methods of 

 Estimating Titanium and Fluorine / by II. E. Merwin. 



That the orange-colored solution obtained by treating 

 titanium sulphate with hydrogen peroxide could be used in 

 the determination of titanium was made known by Weller.* 

 In the application of Weller's method to rock analysis Dun- 

 ningtonf found that in order to obtain results that were at all 

 satisfactory the pyrosulphate melt usually employed as a means 

 of rendering the titanium soluble must be dissolved in sul- 

 phuric acid of at least 5 per cent strength. Bailey and Daw- 

 son;}; concluded that the color of such titanium solutions is 

 due to a soluble form of titanium trioxide. Hillebrand§ has 

 pointed out that fluorine bleaches this color to a marked 

 degree. Steiger| has applied this bleaching effect to the esti- 

 mation of small amounts of fluorine. It is the purpose of 

 this paper to show that large amounts of alkali sulphates have 

 a bleaching action similar to fluorine, and further, that both 

 rising temperature and addition of free acid intensify the 

 colors thus bleached. Finally, methods of analysis taking 

 account of these facts are described. 



The following solutions were used in the experimental work: 

 Standard titanium solution containing -001 g. Ti0 2 and about 

 *1 g. H 2 S0 4 per l cc . This was made by gently heating an 

 intimate mixture of 1 g. of Ti0 2 and 3 g. of ammonium per- 

 sulphate* till the vigorous reaction had ceased, driving off the 

 ammonium sulphate, treating the residue with 20 cc of strong 

 sulphuric acid, heating to fuming and, when cold, pouring into 

 about 800 cc of cold water. 



The suspended titanium salt soon dissolved, after which 

 57'5 0C of strong sulphuric acid and water to make up to 1000 cc 

 were added. If pure Ti0 2 is at hand, this is a most expedi- 

 tious method of obtaining a solution free from fluorine and 

 notable amounts of alkali salts. The precaution of precipitat- 

 ing and weighing the Ti0 2 in 50 cc or more of the solution 

 should not be neglected. 



Fluorine solution, containing '001 g. of fluorine per l cc , 

 made from recrystallized, washed, and strongly ignited sodium 

 fluoride. 



* Ber. Deutsch chem. GeselL, vol. xv, p. 2593, 1882. 

 \ Jour. im. Chem. Soc, vol. xiii, p. 210, 1891. 



X Studies from the Phys. and Chem. Laboratories of Owens Coll., vol. i, 

 p. 216, 1893. 



§ Jour. Am. Chem. Soc., vol. xvii, p. 718, 1895. 

 j| lbid.,vol. xxx, p. 219, 1908. 



