12  THE  PARIS  EXPOSITION. 
in  which  the  hippuric  acid  is  converted  into  the  benzoic  by  the  action  of 
hydrochloric  acid. 
Armet  de  Lisle,  of  Nogent  sur  Marne,  has  a  good  display  of  quinine 
salts  and  other  cinchona  products. 
Tessier  de  Mothey  &  Co.,  of  Metz,  exhibited  fluosilicic  acid  and  the  fluo- 
silicates  of  potash  and  soda,  and  these  alkalies  in  a  caustic  state,  and  have 
introduced  a  process  for  extracting  potash,  based  on  thdr  cheap  furnace 
process  for  obtaining  fluosilicic  acid  by  the  action  of  heat  on  a  mixture  of 
silica,  clay  and  fluor  spar,  and  conducting  the  gases  into  a  chamber  con- 
stantly wet,  so  as  to  decompose  the  fluoride  of  silicon  and  condense  the 
fluosilicic  acid.  With  this  they  extract  the  alkalies  from  their  chlorides 
and  sulphates. 
M.  Laray,  of  Paris,  in  a  very  unpretending  case,  exhibited  specimens 
of  metallic  thallium  and  its  derivatives,  among  which  was  a  thallium  glass 
of  great  density  and  marked  optical  properties,  and  also  ethyl-thallic 
alcohol  of  sp.  gr  3-600.  There  were  other  specimens  of  thallium  in  the 
Exhibition,  particularly  that  of  Mr.  Crookes.  Thallium  was  the  metallic 
novelty  of  the  English  Exhibition  of  1862.  In  the  Paris  Exposition, 
Indium,  the  newest  of  the  metals,  was  the  great  chemical  novelty.  M. 
Richter,  of  Friburg,  exhibited  two  bars  of  this  metal,  weighing  more  than 
a  pound,  and  valued  at  $3,600.  It  looks  like  cadmium,  and  many  of  its 
properties  are  like  it.  It  takes  its  name  from  the  indigo-blue  color  of  its 
spectrum  line.    A  gold  medal  was  awarded. 
It  will  not  do  to  pnss  by  the  unattractive  collection  of  M.  Robinet,  the 
S^retary  of  the  Pans  Congress.  It  consists  of  v/aters  of  various  sources, 
selected  from  among  more  than  2,000  specimens  he  has  analysed,  repre- 
senting the  rivers  of  France  and  many  of  the  noted  rivers  of  Europe.  M. 
Robinet  is  engaged  in  the  preparation  of  a  hydrographic  dictionary  of 
France,  and  has  laboriously  pursued  his  investigations  to  render  it  a  re- 
liable text  book  on  the  potable  waters  of  that  country,  treated  geographi- 
cally, geologically,  chemically  and  in  reference  to  agriculture  and  public 
health. 
The  collections  of  anilin  dye  colors  in  the  French  department  were 
particularly  brilliant.  John  Casthelaz  &  Co.,  of  Paris,  exhibited  a  rich 
collection  of  naphthalin  and  benzole  derivatives  by  nitric  acid,  including 
anilin,  picric  and  benzoic  acids.  They  use  the  nitric  acid  from  two  tons 
of  nitrate  of  soda  per  day  in  producing  color  bases  from  benzole  and 
toluole,  and  in  making  benzoic  acid  artificially  from  naphthalin.  one  of 
the  most  ingenious  and  important  new  processes  of  productive  chemistry. 
(For  process  see  page  118  of  this  Journal  for  1868.) 
Coblentz  Brothers,  Paris,  had  a  beautiful  collection,  among  which 
are  nitrobenzol,  binitrobenzol,  binitrotoluol,  toluyldiamin,  paranilin,  phe- 
notoluol,  etc.  This  firm  have  simplified  the  anilin  process.  The  old 
Fuschine  Company,  of  Lyons,  exhibited  magnificent  specimens  of  muriate 
of  rosanilin,  and  Messrs.  Poirrier  *&  Chappel,  ot Paris,  showed  their  "  Paris 
