1889.] 



Zirconium and its Atomic Weight. 



85 



with such violence at first, and the resulting zirconia is so extremely 

 light that, though every care was taken, varying results were got, 

 even in igniting very gently over the bunsen burner, some as low as 

 43 per cent, of oxide instead of 43 '3 at least. On carefully watching, 

 it was seen that minute particles of zirconia were being carried out of 

 the crucible, although the cover fitted well. This loss was only 

 avoided by enclosing the crucible within a second larger one, whose 

 cover fitted quite closely and only communicated with the external 

 atmosphere by a drawn-out neck, so that there were no air-currents. 

 Even then, if the crucible was placed over the blowpipe flame at once, 

 loss occurred and it was necessary in every case to commence the 

 operation over the flame of a bunsen burner, and then after half an 

 hour to transfer to the blowpipe. 



Part of the determinations were made by Berzelius in the wet way 

 — that is, the zirconia was first precipitated by means of ammonia, 

 and then the sulphuric acid determined in the filtrate by precipitation 

 with barium chloride. 



Having satisfied myself by careful comparative experiments that 

 the results of both methods, under favourable conditions, correspond, 

 I decided to adopt the dry method, viz., that of conversion of the 

 sulphate into the oxide by ignition — 



(a.) Because it involved the least complicated operations and the 



fewest assumptions. 

 (&.) Because under some circumstances basic zirconium sulphate is 



thrown down when ammonia is added to a solution of the 



sulphate. 



In the following paragraphs are given the determinations of Ber- 

 zelius and Mats Weibull from the sulphate, followed by those based 

 upon my own experiments. 



Berzelius's Determination (' Pogg. Ann..,' vol. 4, p. 126). 



From the analysis of the sulphate : — 

 S0 3 : Zr0 2 : : 100 



Mean 



75-84 

 75-92 

 75-80 

 75-74 

 75-97 

 75-85 



75-853 



Zr0 2 : 2S0 3 

 Zr : O 

 Zr : H . 



1-5171 : 2 

 5;591 : 1 

 #•23 : 1 



