1889.] 



Zirconium and its Atomic Weight. 



11 



In order, however, to have a further guarantee that the producb 

 used for the determination of atomic weight had a definite composi- 

 tion and character, the experiments described later for the determina- 

 tion of atomic weight were made upon four portions, whose final 

 treatment was as essentially different as possible. 



Portion A was precipitated from an acid solution of the sulphate 

 by the addition of hydrogen peroxide containing no other impurity 

 than sulphuric acid. 



Portion B was transformed into the tetrachloride by heating the 

 zirconia with charcoal in a current of chlorine and then reprecipitated 

 by ammonia. 



Portion G was crystallised out from concentrated sulphuric acid by 

 boiling off part of the excess of acid and then allowing to cool. 



Portion D was further recrystallised from hydrochloric acid and 

 washed very thoroughly with a mixture of hydrochloric acid, alcohol, 

 and ether as described. v 



Stability of the Zirconium Salts. 



In the case of zirconium it was evident that the number of com- 

 pounds of a simple character and of sufficient stability to afford a 

 good basis for a determination of atomic weight must be very 

 limited. The principles, therefore, on which it was decided to 

 proceed were — 



(a.) To prepare zirconia by several independent methods. 



(6.) To ascertain the most stable salt (or salts if more than one 

 should prove stable), and the most simple transformation of 

 this which would lead to an accurate determination. 



Indeed it seems to me in general that unless there are two or more 

 salts of a very stable character, lhat reliance should lean rather 

 towards the production of the raw material by independent processes, 

 than towards the confirmation of results obtained from a more stable 

 salt by means of values derived from observations on one that is less 

 stable. 



The methods previously used in the determination involved — 

 (1.) Relation of zirconium sulphate to oxide. 



(a.) Direct conversion by ignition. 

 (b.) Via BaS0 4 by precipitation. 



Mats Weibull (loc. cit.) ; Berzelius (' Pogg. Ann.,' vol. 4, p. 126). 

 (2.) Relation of Zr (in Zr0 3 ) to CI (in AgCl). 



(a.) By analysis of ZrCl 4 . 

 (&.) By analysis of ZrOCl 2 . 



Hermann (' Journ. Pr. Chem.,' vol. 97, p. 323). 



