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 Ti0 2 in percentages 

 referred to TiCl 4 as 100, and in a fifth column the quantity of TiCl 4 pro- 

 portional to 100 parts of AgCl : 



TiCl. TiO T AgCl. Percent. TiO. 2 . AgCl Ratio. 



.885 grm. .379 grm. 2.661 grm. 42.825 33- 2 S8 



2.6365 " 1. 120 " 7.954 " 42.481 33-147 



I.7I57 " -73 2 " 5- I 72 " 42.665 33.173 



3.0455 " 1.322 " 9.198 " 43.423 33-100 



2.4403 " 1.056 ' 7.372 " 43-273 33.102 



Mean, 42.933, .121 33.156, .019 



If we directly compare the AgCl with the Ti0 2 we shall find 100 parts 

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



14.243 

 14.081 

 14-153 

 H.373 

 14.324 



Mean, 14.235, .036 



Shortly after the appearance of Rose's paper, MosanderJ published 

 some figures giving the 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- 

 ings 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. 



t Poggend. Annalen, 15, 145. Berz. I,ehrbuch, 3, 1210. 



j Berz. Jahresbericht, 10, 108. 1831. 



