190 THE ATOMIC WEIGHTS. 



TITANIUM. 



The earliest determinations of the atomic weight of titanium are due 

 to Heinrich Rose.* In his first investigation he studied the conversion 

 of titanium sulphide into titanic acid, and obtained erroneous results ; 

 later, in 1829, he published his analyses of the chloride, f This compound 

 was purified by repeated rectifications over mercury and over potassium, 

 and was weighed in bulbs of thin glass. These were broken under water 

 in tightly stoppered flasks ; the titanic acid was precipitated by ammo- 

 nia, and the chlorine was estimated as silver chloride. The following 

 results were obtained. In a fourth column I give the TiO.^ in percentages 

 referred to TiCl^ as 100, and in a fifth column the quantity of TiCl^ pro- 

 portional to 100 parts of AgCl : 



Mean, 42.933, ±.121 33-156, ±.019 



If we directly compare the AgCl with the TiO^ we shall find 100 parts 

 of the former proportional to the following quantities of the latter: 



14.243 

 14.081 

 14-153 

 14-373 

 14.324 



Mean, 14.235, dz .036 



Shortly after the appearance of Rose's paper, Mosander;]: published 

 some figures giving tlie percentage of oxygen in titanium dioxide, from 

 which a value for the atomic weight of titanium was deduced. Although 

 no details are furnished as to experimental methods, and no actual weigh- 

 ino-s are given, I cite his percentages for whatever they may be worth : 



40.814 



40.825 



40.610 



40. 1 80 



40.107 



40.050 



40.780 



40.660 



39.830 



Mean, 40.428 



* Gilbert's Annalen,- 1823, 67 and 129. 



tPoggend. Annalen, 15, 145. Berz. Lehrbuch, 3, 1210. 



j Berz. Jahresbericht, 10, 108. iS.^i. 



