210 THE ATOMIC WEIGHTS. 



might have been contaminated with SiCl^, an impurity 

 which would lower the value deduced for the atomic weight 

 under consideration. Accordingly, in order to eliminate all 

 such possible impurities, this process was resorted to : the 

 chloride, after rectification over mercury and potassium, was 

 acted upon by dry ammonia, whereupon the compound 

 TiCl4.4NH3 was deposited as a white powder. This was 

 ignited in dry ammonia gas, and the residue, by means of 

 chlorine, was reconverted into titanic chloride, which was 

 again repeatedly rectified over mercury, potassium, and 

 potassium amalgam. The product boiled steadily at 135°. 

 This chloride, after weighing in a glass bulb, was decomposed 

 by water, the titanic acid was precipitated by ammonia, and 

 the chlorine was estimated in the filtrate as silver chloride. 

 Three analyses were performed, yielding the following re- 

 sults. I give the actual weighings : 



1.470 grm. TiCl^ gave 4.241 grm. AgCl and .565 grm. TiO.^. 

 2.330 " 6.752 " .801 



2.880 " 8.330 " 1.088 



The ".801 " in the last column is certainly a misprint for 

 .901. Assuming this correction, the results may be given 

 in three ratios, thus : 



Per cent. TiO.Jrom TiCl^. TiCl^ : 100 AgCl. TiO^ : zoo AgCl. 

 38.435 34-662 13.322 



38.669 34-508 13-344 



37-778 34-574 13-061 



Mean, 38.294, dz .180 34.581, ± .030 13.242, dr .061 



These three ratios give three widely divergent values for 

 the atomic weight of titaniun ; 



From per cent. TiOj Ti = 36.063, ± .519 



" AgCl : TiOj " = 43.841, i+r .350 



" AgCl : TiCl, " = 56.386, ± .181 



General mean " -= 52.191, rh .153 



The value assumed by Demoly is 56 ; who employs but 

 one ratio and ignores practically the others. 



