Am.  J(  ur.  Pharm.  \ 
May,  1902.  / 
Atomic  Weight  Tables. 
231 
liquid  is  weighed  must  be  taken  into  account,  and  this  correction 
must  be  made  for  each  and  every  liquid  experimented  with,  as  each 
liquid  has  its  own  rate  of  expansion,  and  this  rate  of  expansion 
must  be  ascertained  and  the  scale  for  it  arranged  beforehand. 
The  paper  of  Dr.  Hatcher's  recalls  the  fact  that  that  method  of 
taking  specific  gravity  was  shown  by  me  to  the  class  when  I  was  a 
quiz  master  to  the  Zeta  Phi  Society,  1875  or  '77. 
An  easy  method  of  taking  specific  gravity  of  bodies  soluble  in 
water  is  given  in  "  Ganot's  Physics,"  and  is  as  follows:  Weigh  the 
body  in  air,  then  in  some  liquid  the  specific  gravity  of  which  has 
been  ascertained,  and  in  which  it  is  insoluble,  and  multiply  its  weight 
by  the  specific  gravity  of  the  liquid,  then  divide  this  product  by  the 
loss  sustained  when  immersed  in  the  liquid.  The  result  is  the  spe- 
cific gravity  sought. 
A  COMPARATIVE  STUDY  OF  ATOMIC  WEIGHT  TABLES. 
By  M.  I.  Wilbert. 
That  the  active  pharmacist  is  interested  in  the  present  contro- 
versy on  atomic  weights  is  admitted  ;  to  what  extent  it  might  or 
will  affect^him  in  the  ordinary  routine  of  his  business  has  probably 
not  been  considered. 
Those  of  us  who  studied  chemistry  when  hydrogen  was  1  and 
oxygen  always  16,  do  not  perhaps  realize  the  difficulties  that  beset 
the  student  and  teacher  of  chemistry  at  the  present  day,  when  the 
atomic  weights  of  the  various  elements  vary  with  the  text-book 
that  is  used  or  the  table  that  is  consulted.  A  great  amount  of 
work  has  been  done  in  this  connection  in  the  last  twenty  years,  and 
the  leading  chemists  of  the  world  have  long  ago  refused  to  be 
bound  by  arbitrarily  proposed  laws  ;  and  among  other  things  have 
discovered  that  our  system  of  enumeration,  for  instance,  is  not 
necessarily  a  factor  in  chemical  relations,  so  that  instead  of  the 
various  elements  being  related  to  each  other  in  some  mathematical 
proportion,  we  find  that  these  proportions  are  at  times  fragmentary 
or  fractional  to  a  degree  that  is  not  at  all  in  keeping  with  the  aver- 
age pharmacist's  capacity  in  mental  arithmetic. 
But  there  is,  no  doubt,  something  more  startling  and  revolutionary 
at  the  bottom  of  it  all.  There  are  so  many  physical  phenomena  to 
explain  that  we  constantly  hear  of  the  possibility  of  our  long- 
