34 
Report  on  Atomic  Weights. 
Am.  Jour.  Pharm. 
January,  1920. 
by  the  determinations  of  Lecoq  de  Boisbaudran  vary  from  69.70 
to  70.12,  the  last  one  being  very  near  the  new  value. 
Zirconium. — From  the  ratio  between  zirconium  chloride  and  sil- 
ver, Venable  and  BelU^  find  Zr  =  91 .76.  Although  this  determination 
is  regarded  as  preliminary,  the  authors,  by  pointing  out  sources  of 
error  in  all  previous  values,  believe  the  new  one  to  be  the  most  prob- 
able. It  seems  best,  however,  to  await  the  complete  investigation 
before  changing  the  value  heretofore  accepted. 
Tin. — Baxter  and  Starkweather,^^  by  electrolyses  of  stannic 
chloride,  find  Sn  =  118.703  when  CI  =  35.457.  This  is  in  complete 
agreement  with  Briscoe's  determination,  Sn  =  118.698.  The  value 
118.70  has  already  been  adopted  by  the  committee. 
TelIvURIum. — Staehler  and  Tesch,^^  from  careful  syntheses  of 
tellurium  dioxide,  find  Te  =  127.51,  which  is  confirmatory  of  the 
accepted  value  127.5. 
Yttrium. — Hopkins  and  Balke,^''  by  conversion  of  YtQOs  into 
Yt2Cl3,  find  Yt  =  88.9.  The  ordinary  sulphate  method  is  shown  to 
be  inaccurate.  In  a  later  investigation  Kremers  and  Hopkins 
determined  the  ratio  between  yttrium  chloride  and  silver,  and  found 
Yt  =  89.33.  Since  this  method  is  the  most  trustworthy,  the  value 
given  by  it  should  be  adopted.  The  other  sulphate  determinations 
are  questionable. 
Samarium. — The  atomic  weight  of  samarium  has  been  determined 
by  Stewart  and  James from  the  ratio  between  the  chloride  and  silver. 
The  value  found  is  150.44,  which  is  essentially  that  given  in  the  table. 
No  change  is  needed. 
Dysprosium. — Engle  and  Balke,^^  by  conversion  of  the  oxide 
into  the  chloride,  found  Dy  =  164.228.  I^ater,  by  the  same  method, 
Kj'emers,  Hopkins  and  Engle^^  found  Dy  =  163.83.  This  dis- 
cordance, like  that  already  shown  for  yttrium,  led  the  last-named 
chemists  to  determine  the  ratio  between  dysprosium  chloride  and 
silver,  which  gave  162.52.    The  earlier  method  is  discredited  and 
17  J.  Amer.  Chem.  Soc,  39:  1598,  1917. 
18  Proc.  Nat.  Acad.  Sci.,  2:  718,  1916. 
1^  Z.  anorg.  allgem.  Chem.,  98:  i,  1916. 
20  /.  Am.  Chem.  Soc,  36:  2332,  1916. 
21  Ibid.,  41 :  718,  1919. 
22  /.  Am.  Chem.  Soc,  39:  2605,  1917. 
23  Ibid.,  39:  67,  1917. 
24  Ibid.,  40:  598,  1918. 
