186 
VARIETIES. 
containing  logwood — indeed  on  all  inks.  Many  other  plain  inks  were 
exhibited,  and  their  proportions  described — as  gallo-sumach  inks,  iny- 
robalens  ink,  Runge's  ink, — inks  in  which  the  tannogallite  of  iron  was 
kept  in  solution  by  nitric,  muriatic,  sulphuric,  and  other  acids,  or  by 
oxalate  of  potash,  chloride  of  lime,  &c.  The  myrobalans  ink  was  recom- 
mended as  an  ink  of  some  promise  for  durability,  and  as  the  cheapest  ink 
it  was  possible  to  manufacture.  All  ordinary  inks,  however,  were  shown 
to  have  certain  drawbacks,  and  the  author  endeavored  to  ascertain  by  ex- 
periment, whether  other  dark  substances  could  be  added  to  inks,  to  impart 
greater  durability  to  writings  made  with  them,  and  at  the  same  time  pre- 
vent those  chemical  changes  which  were  the  cause  of  ordinary  inks  fading. 
After  experimenting  with  various  substances,  and,  among  others,  with 
Prussian  blue  and  indigo  dissolved  in  various  ways,  he  found  the  sulphate 
of  indigo  to  fulfil  all  the  required  conditions  ;  and,  when  added  in  the  pro- 
per proportion  to  a  tannogallate  ink,  it  yielded  an  ink  which  is  agreeable 
to  write  with,  which  flows  freely  from  the  pen,  and  does  not  clog  it,  which 
never  moulds,  which,  when  it  dries  on  the  paper,  becomes  of  an  intense 
pure  black,  and  which  does  not  fade  or  change  its  color,  however  long  kept. 
The  author  pointed  out  the  proper  proportions  for  securing  these  proper- 
ties, and  showed  that  the  smallest  quantity  of  the  sulphate  of  indigo  which 
could  be  used  for  this  purpose,  was  eight  ounces  for  every  gallon  of  ink. 
The  author  stated  that  the  ink  he  preferred  for  his  own  use  was  composed 
of  twelve  ounces  of  galls,  eight  ounces  of  sulphate  of  indigo,  eight  ounces 
of  copperas,  a  few  cloves,  and  four  or  six  ounces  of  gum-arabic,  for  a  gal- 
lon of  ink.  It  was  shown  that  immersing  iron  wire  or  filings  in  these 
inks,  destroyed  their  durability  as  much  as  similar  treatment  destroyed  or- 
dinary inks.  He  therefore  recommended  that  all  legal  deeds  or  documents 
should  be  written  with  quill  pens,  as  the  contact  of  steel  invariably  destroys 
more  or  less  the  durability  of  every  ink.  The  author  concluded  his  Paper 
with  a  few  remarks,  on  copying  inks,  and  indelible  inks,  showing  that  a 
good  copying  ink  has  yet  to  be  sought  for,  and  that  indelible  inks,  that  will 
resist  the  penciiings  and  washings  of  the  chemist,  and  the  forger,  need 
never  be  looked  for. — Load.  Civ.  and  Arch.  Jour.,  August  1855,  and  Frank. 
Inst.  Jour. 
On  the  Extraction  of  Metals  from  the  Ore  of  Platinum.  By  M.  Fremt. — 
M.  Fremy  treated  of  the  preparation  of  osmium,  rhodium,  and  iridium, 
from  the  residues  of  the  platinum  ores.  The  preparation  of  osmium  accord- 
ing to  the  old  method  is  attended  with  great  difficulties  and  actual  danger. 
M.  Fremy  proposed  to  prepare  osmium  by  passing  atmospheric  air  over  the 
residual  ore,  heated  in  a  porcelain  tube.  The  volatile  osmic  acid  is  con- 
densed in  glass  balloons,  and  the  less  volatile  oxide  of  ruthenium  is  found 
at  the  extremity  of  the  heated  tube.  The  rhodium  remaining  in  the  re- 
sidual mass  is  separated  from  the  other  metal  contained,  by  chlorine  gas  at 
a  high  temperature. — Frank.  Inst.  Jour. 
