154  Pharmaceutical  Meeting.  {AmMirch.mt.rm- 
comparison,  as  most  elements  form  oxides  or  compounds  with 
oxygen. 
Professor  Smith  referred  to  some  of  the  difficulties  in  determining 
atomic  weights,  and  illustrated  the  same  with  the  work  which  he 
and  his  students  have  been  carrying  on  for  a  number  of  years  in 
the  Harrison  Chemical  Laboratory,  particularly  on  palladium  and 
tungsten. 
Berzelius  gave  the  value  of  100  to  oxygen,  but  this  is  no  longer 
retained.  Three  systems  have  been  used  in  calculating  the  molec- 
ular weights  of  organic  compounds:  (i)  H  =  I  ;  C  =  12;  O  = 
16 :  (2)  H  =  i-oo8  ;  C=  12 ;  O  =  16 :  (3)  H  =  1  ;  C  ==  1 1-91 ; 
O  ==  15*88.  The  speaker  showed  in  a  few  instances  what  great 
differences  would  result  in  the  calculation  of  the  molecular  weights 
of  oxalic  acid,  or  the  sugar  C12H22Ou  with  the  three  systems. 
Furthermore,  inasmuch  as  the  great  work  of  Beilstein,  in  which 
over  70,000  organic  compounds  are  described,  is  based  on  the  first 
of  these  systems,  it  would  mean  a  recalculation  of  all  these  com- 
pounds, for,  as  Morley  has  shown,  if  H  ==  1,  then  oxygen  equals 
15-88,  and  if  oxygen  equals  16,  then  hydrogen  equals  1-008. 
Professor  Smith  referred  to  the  labors  of  the  committee  of  the 
German  Chemical  Society,  and  compared  the  international  and 
didactic  tables  published  by  them.  He  then  gave  some  of  the 
arguments  in  favor  of  the  standard  that  hydrogen  equals  I  as  fol- 
lows: (1)  It  is  the  original  Daltonian  standard  ;  (2)  it  is  the  most 
natural  basis,  because  hydrogen  is  the  lightest  atom  known  and  is 
the  standard  for  determining  the  densities  of  gases  and  valence  ;  (3) 
if  oxygen  is  made  the  standard,  then  all  vapor  densities  must  be 
changed;  (4)  with  the  physicist  hydrogen  is  the  standard;  (5) 
hydrogen  has  a  uniform  rate  of  expansion ;  (6)  the  difficulty  of 
teaching  that  H  =  1-008. 
The  following  are  some  of  the  features  in  favor  of  the  standard 
oxygen  equals  1 6-oo:  (1)  Few  elements  can  be  compared  directly 
with  hydrogen,  of  all  the  elements  known,  but  seven  or  eight  have 
had  their  atomic  weights  compared  directly  with  oxygen;  (2)  with 
oxygen  as  the  standard  the  atomic  weights  of  a  very  large  number 
of  the  elements  are  whole  numbers,  as  is  seen  in  a  comparison  of 
the  international  (O  =  16-00),  and  the  didactic  (H  =  1)  tables;  (3) 
this  is  of  very  material  importance  in  making  calculations  in  quan- 
titative analysis;  and  (4)  must  be  less  burdensome  to  the  memory  ; 
