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Atomic  Weight  Tables. 
Am.  Jour.  Pharm 
May,  1902. 
cherished  hypothesis  of  the  atom  being  an  entirely  erroneous  one, 
and  that  we  will  wake  up  some  morning  to  a  double-headed  leader 
in  the  morning  papers  announcing-  the  discovery,  or  perhaps  the 
actual  demonstration  of  the  unity  of  matter  and  the  possible  trans- 
mutation of  the  various  elementary  bodies. 
But  what  to  do  in  the  meantime  is  the  question  that  is  troubling 
many  an  able  scientist.  If  we  glance  over  the  accompanying  list  of 
the  elements  and  their  corresponding  atomic  weights,  we  will  real- 
ize that  there  is  very  little  or  no  uniformity  between  them  ;  and, 
what  is  more,  every  one  will  admit,  that  if  we  should  use  any  one  of 
these  tables,  the  results  of  our  computation  or  work  would  not 
agree  with  the  results  obtained  by  some  one  who  was  using  one  of 
the  other  tables. 
But,  first,  a  few  words  as  to  the  origin  of  these  tables.  The  first 
one  is  from  Professor  Ostwald's  new  book  on  "  Anorganische 
Chemie,"  and,  with  the  single  exception  of  hydrogen,  gives  the  same 
figures  as  the  table  of  atomic  weights  in  the  German  Pharmacopoeia. 
The  latter  book  rounds  out  the  figures  for  hydrogen  at  the  sec- 
ond decimal,  making  it  i*oi  instead  of  i-oo8. 
The  second  list,  hydrogen-i,  is  from  Professor  Clark's  table  of 
comparative  atomic  weights  (1900).  It  will  be  noted  that  these  two 
tables  do  not  exactly  correspond  in  their  relative  figures,  nor  do 
they  agree  in  all  particulars  with  the  tables  published  by  the  Ger- 
man Chemical  Society.  This  particular  H-i  table  was  chosen 
because  it  has  been  used  in  several  text-books  on  chemistry  that  are 
now  in  use  in  this  country. 
The  third  table  is  taken  from  the  Pharmacopoeia  of  the  United 
States  for  1890. 
The  fourth  list  is  from  the  atomic  weights  as  given  in  the  same 
standard  for  1880. 
In  explanation  we  might  say  that  niobium  is  duplicated  under 
columbium,  and  the  revised  weights  for  didymium  are  given  under 
neo  and  praseodidymium  ;  these  are  matters  of  detail,  however,  and 
are  of  but  secondary  importance. 
The  important  ieature  in  connection  with  a  comparative  study  of 
a  table  ot  this  kind  is  a  comparison  of  the  atomic  weights  of  the 
more  common  and,  consequently,  more  important  elements.  If,  for 
instance,  we  take  into  consideration  the  immense  amount  of  work 
that  has  been  done  in  the  field  of  organic  chemistry,  confined  almost 
