The  power  of  analysis,  which  enables  us  to  detect  adulterations,  has  been
invaluable  to  the  public  health,  and  would  be  much  more  so,  if  it  were
possible  to  obviate  the  difhculties  which  have  prevented  the  operation  of
recent  legislation  on  thb  subject

We  have  another  proof  of  the  utility  of  this  science  in  its  application  to
medicine ;  and  the  estimation  in  which  it  is  held  by  the  medical  profession
is  the  true  index  of  its  value  in  the  diagnosis  and  treatment  of  disease.  The
largest  developments  of  chemistry,  however,  have  been  in  connexion  with
the  useful  arts.  What  would  now  be  the  condition  of  calico-printing,
bleaching,  dyeing,  and  even  agriculture  itself,  if  they  had  been  deprived  of
the  aid  of  theoretic  chemistry  ?


AI>DBBS8«  IV

For  ezttnplet  Aniline — fifst  discovered  in  ooal-tar  by  Dr.  Hoftnanni  who
k«  to  admirably  developed  its  properties — is  now  most  extensively  used  as
the  basis  of  red,  blae»  violet,  and  green  dyes.  This  important  discovery  will
probably  in  a  few  years  render  this  country  independent  of  the  world  for
dye-stttffii ;  and  it  is  more  than  probable  that  England,  instead  of  drawing
her  d je-stnffii  from  foreign  countries,  may  herself  become  the  centre  from
which  all  the  world  will  be  supplied*

It  b  an  interesting  fact  that  at  the  same  time  in  another  branch  of  this
sdeiiee.  M.  Touraet  has  lately  demonstrated  that  the  colours  of  gems^  such
as  the  emerald,  aqua*inarina,  amethyst,  smoked  rock-crystalj  and  others,  are
doe  to  volatile  hydrocarbons,  first  noticed  by  Sir  David  Brewster  in  clouded
topaz,  aod  that  they  are  not  derived  from  metallic  oxides,  as  has  been  hitherto
believed.
