THE 
AMERICAN  JOURNAL  OF  PHARMACY. 
MARCH,  1862. 
RESEARCHES  ON  THE  MOLECULAR  DISSYMMETRY  OF  NATURAL 
ORGANIC  PRODUCTS.  By  L.  Pasteur,  Member  of  the  Chemical 
Society  of  Paris.  Presented  to  the  Chemical  Society  of  Paris,  January  20 
and  Febuary  3,  1860.  Translated  from  "  Le5ons  de  Chimie  professees 
en  I860."    By  W.  S.  W.  Ruschenberger,  M.  D.,  U.  S.  Navy.* 
SECOND  LECTURE. 
If  we  consider  material  objects,  whatever  they  may  be,  in 
the  relation  of  their  forms  and  of  the  repetition  of  their  identical 
parts,  we  shall  not  be  slow  to  perceive  that  they  are  distributed 
in  two  great  classes,  thus  characterized :  Some  placed  before  a 
mirror  give  an  image  which  to  them  is  superposable  ;  the  image 
of  others  would  not  cover  them  although  it  faithfully  reproduces 
all  their  details.  A  straight  stair,  a  stem  of  distich  leaves,  a 
cube,  the  human  body,  are  bodies  in  the  first  category.  A 
winding  stair,  a  stem  of  leaves  spirally  inserted,  a  screw,  a  hand, 
an  irregular  tetrahedron,  are  so  many  forms  of  the  second  group. 
These  latter  have  no  plane  of  symmetry. 
We  know  on  the  other  hand  that  compound  bodies  are  ag- 
gregates of  identical  molecules,  themselves  formed  of  assem- 
blages of  elementary  atoms  distributed  according  to  laws  which 
regulate  the  nature,  the  proportion,  the  arrangement  of  them. 
The  individual,  for  every  compound  body,  is  its  chemical  mole- 
cule, and  this  is  a  group  of  atoms,  not  a  group  pell-mell ;  there  is, 
on  the  contrary,  a  very  determinate  arrangement.  Such  is  the 
manner  in  which  all  physicists  represent  the  constitution  of 
bodies. 
This  stated,  it  would  have  been  very  astonishing  had  not  na- 
ture, so  varied  in  her  effects,  and  whose  laws  permit  the  existence 
of  30  many  species  of  bodies,  offered  in  the  atomic  groups  of 
♦Continued  from  page  16. 
7 
