is　discovered　for　the　carbon　which　forms　nearly　the
  whole　of　its　composition；　at　which　time　THE　perfect
  ink　can　be　said　to　have　been　discovered。
  CHAPTER　XVII。
  INK　PHENOMENA。
  CONDITION　OF　INK　WHEN　FIRST　PLACED　ON　PAPERITS
  METAMORPHOSIS　AND　AFFINITIESIGNORANCE　OF　THE
  FORGER　AS　TO　ITS　ORIGINAL　ENVIRONMENTTREATMENT
  OF　OLD　INK　MARKSHOW　PAPER　MAY　DISCOLOR
  INKTHE　USES　OF　ACID　IN　INKVEHICLES
  TO　HOLD　INK　PARTICLES　AND　PRESERVE　THEMINKS
  FIVE　CENTURIES　OLD　DO　PRESERVE　THEIR
  GLOSSSOME　CAUSES　OF　INK　DISINTEGRATIONWHEN
  INK　BECOMES　IRRESPONSIVE　TO　THE　ELEMENTS
  DEMONSTRATED　TRUTHS　ABOUT　INK　CONSTITUENTS　AND
  COLOR　PHENOMENANATURAL　EVOLUTION　OF　AN
  INK　MARKLENGTH　OF　TIME　REQUIRED　TO　BECOME
  BLACKFIRST　INDICATIONS　OF　AGEDISAPPEARANCE
  OF　INK　QUALITIESARTIFICIAL　AGING　OF　INKTESTS
  FOR　IT　AND　HOW　TO　CONFIRM　THEMBLEACHING　AND
  REMOVAL　OF　INK　FROM　PAPER　CRIMINALLY　CONSIDERED
  CHEMISTRY　OF　SUCH　MARKSTHEIR　RESTORATION
  VARIATIONS　IN　METHODS　WHICH　CAN　BE
  EMPLOYED。
  ALL　inks　when　first　placed　on　paper　are　of　course
  in　a　fluid　state。　Gradual　evaporation　of　moisture
  causes　a　change　not　only　in　color　but　in　the　case　of
  the　iron　and　gall　inks；　in　their　chemical　constitution；
  being　immediately　affected　by　their　environment；
  whether　due　to　the　character　of　the　paper　on　which
  they　rest；　the　kind　or　condition　of　the　pen　used；　or
  most　important　of　all；　the　elements。　Those　who　use　the
  black　inks　and　chemical　writing　fluids　will　have　noticed
  these　characteristics。　The　pale　brown；　blue　or　green
  as　first　written；　and　the　gradual　change　after　a　short
  period　to　an　approaching　blackness；　are　reactions　due
  largely　to　atmospheric　conditions；　the　oxygen　uniting
  with　that　for　which　it　has　affinity　and　instantly
  beginning　with　TIME　to　make　its　march；　producing
  natural　phenomena；　which　can　be　only　superficially
  imitated　but　never　exactly　reproduced。　When　we
  further　take　into　consideration　that　the　forger　cannot
  always　know　of　the　circumstances　which　surround
  the　placing　of　original　ink　on　paper　and　that　be　cannot
  manufacture　the　TIME　which　has　already　elapsed；
  it　is　not　strange　that　attempted　fraud　can　often　be
  made　evident　and　complete　demonstrations　given　of
  the　methods　employed。
  With　the　passage　of　time；　the　particles　in　some
  inks　which　are　held　together　on　the　paper　by　gummy
  vehicles；　commence　to　disintegrate　and　change　from
  intense　black　to　the　brown　color　of　iron　rust；　the
  〃added〃　color　which　of　itself　is　fugitive　in　character；
  soon　departs；　the　vegetable　astringent　separating
  from　the　iron　salt　decays　gradually　and　disappears
  and　finally　terminates　in　a　mere　stain　or　dust　mark
  which　can　be　blown　off　the　paper。　Sometimes；　the
  written　surface　of　such　paper　can　be　treated　by　carefully
  moistening　it　with　a　decoction　of　nut…galls　or　its
  equivalent　in　the　presence　of　a　weak　acid；　then　if　any
  iron　be　present；　a　measurable　degree　of　restoration　of
  color　will　ensue　and　remain　for　a　short　period。
  Again；　the　discoloration　of　an　iron　ink　may　be　due　to
  the　character　of　the　paper；　if　of　the　cheaper　grades
  and　the　bleaching　compounds　employed　in　their
  manufacture　are　not　thoroughly　washed　out；　then　the
  ink　not　only　begins　to　absorb　oxygen　from　the
  atmosphere　but　the　chlorine　in　the　paper　attacks　it
  and　the　process　of　destruction　is　thereby　hastened。
  The　introduction　of　acid　into　ink　has　two　purposes；
  one　to　secure　more　limpidity；　and　the　other　to　cause
  it　to　penetrate　the　paper　and　in　this　way　bind
  together　the　constituent　particles　of　both　ink　and
  paper。　Most　of　the　chemical　writing　fluids　of　this
  decade　carry　a　superabundance　of　acid　in　their
  composition；　which　in　time　will　burn　through　the　paper
  and　ultimately　destroy　it。
  All　tanno…gallate　of　iron　inks　require　some　vehicle
  to　hold　their　particles　in　a　state　of　suspension；　otherwise
  there　would　be　precipitation　and　such　an　ink
  could　not　be　used。　To　meet　this　requirement　a
  variety　of　gums　are　employed　by　manufacturers；
  gum　acacia　being　the　principal　one。　Its　purpose　is
  threefoldas　before　stated；　to　hold　the　ink　particles
  in　suspensionto　prevent　the　ink　from　flowing　too
  rapidly；　and　after　drying　WITHOUT　blotting；　to　act　as
  an　envelope　to　encase　the　now　fixed　ink　and　prevent
  or　interfere　with　its　absorption　of　an　excess　of　oxygen。
  The　longer　these　latter　conditions　obtain　the　longer
  will　the　ink　retain　its　pristineness；　its　durability　and
  permanence。　The　〃time　proved〃　ink…written　specimens
  of　five　hundred　years　or　more　ago　which　continue
  to　retain　their　original　intense　black　color　and
  〃glossy〃　appearance；　do　not；　however；　yield　any　evidence
  of　the　use　of　vegetable　gums　in　their　composition。
  Where　such　instances　have　been　noticed　the　gloss　is
  invariably　missing。　But；　where　ANY　gloss　is　present；
  it　was　and　is　because　of　the　employment　of　isinglass
  （fish…glue）　as　the　vehicle　to　hold　the　ancient　ink
  particles。
  Hence　the　variations　of　color　seen　in　ancient　paper
  writings；　as　already　stated；　were　due　not　only　to　possible
  imperfect　admixtures　of　the　component　parts　of
  the　inks；　but　to　the　use　of　vegetable　gums　in　their
  preparation。　In　the　course　of　time　these　have　been
  absorbed　by　moisture　which　hastened　disintegration；
  causing　a　gradual　disappearance　of　their　original　blackness
  and　gloss　and　finally　a　return　to　the　rusty　color
  of　oxidized　iron。
  It　therefore　follows；　my　observations　and　deductions
  being　correct；　the　older　a　writing　made　with
  tanno…gallate　of　iron　ink；　where　isinglass　is　the　binder；
  and　which　has　not　been　〃blotted；〃　the　harder　and
  more　impervious　and　irresponsive　it　becomes　to　the
  action　of　the　natural　elements　or　of　chemical　reagents。
  The　truths　demonstrated　in　this　proposition　cannot
  be　denied。　They　fortify　as　certain　that　a　properly
  proportioned　mixture　in　water　of　an　infusion　of　nut…
  galls　or　gallo…tannic　acid　and　sulphate　of　iron；　with
  isinglass　as　the　vehicle　to　bold　the　particles　in　a　state
  of　suspension；　if　written　with　on　good　paper　and　allowed
  to　dry　without　blotting；　in　a　short　time　becomes
  encased　or　enveloped　in　such　vehicle；　which　is　thereby
  rendered　substantially　insoluble　and　absolutely
  prevents　any　extensive　oxidation。　Also；　as　a　further
  consequent　result；　there　is　chemically　created　an
  unchangeable　and　continuing　black　color　more　permanent
  and　durable　than　the　substance　on　which　it　appears。
  With　a　sample　of　standard　commercial　chemical
  writing　fluid；　write　on　〃linen〃　paper　without　blotting
  it；　in　thirty　hours；　if　exposed　to　the　air　and
  from　three　to　five　days　if　kept　from　it；　the　writing
  should　have　assumed　a　color　bordering　on　black；　it
  becomes　black　at　the　end　of　a　month　under　any　conditions；
  and　so　continues　for　a　period　of　about　five
  or　six　years；　when　if　examined　under　a　lens　of　the
  magnification　of　ten　diameters；　there　will　be　a　noticeable
  discoloration　of　the　sides　or　pen　tracks　which
  slowly　spreads　during　a　continuing　period　of　from　ten
  to　fifteen　years；　until　the　entire　pen　marks　are　of　a
  rusty　brown　tint。　A　species　of　disintegration　and
  decay　is　now　progressing　and　when　approximately
  forty　years　of　age；　has　destroyed　all　ink　qualities。
  If；　however；　〃chemical　writing　fluid〃　is　first　treated
  by　exposure　to　the　fumes　of　an　ammoniacal　gas；　a
  〃browning〃　of　the　ink　occurs；　not　only　of　the　pen
  tracks　but　of　the　entire　ink　mark。　If　examined　now
  with　a　lens；　the　ink　is　found　to　be　thin　enough　to　permit
  the　fibre　of　the　paper　to　be　seen　through　it；　thus　indicating
  artificial　age。　Furthermore；　if　a　20　per　cent
  strength　of　hydrochloric　acid　be　applied；　the　〃added〃
  color　（usually　a　blue　one）　is　restored　to　ITS　original
  hue；　alike　experiment　on　〃time〃　aged　ink　gives
  only　the　yellow　brown　tint　of　pure　gall　and　iron
  combinations；　the　〃added〃　color　having　departed　caused
  by　its　fugitive　characteristics。　Again；　if　a　solution　of
  chlorinate　of　lime　or　soda　be　applied；　the　ink　mark
  is　instantly　bleached；　where　in　the　case　of　honest　old
  ink　marks；　it　takes　considerable　time　to　even　approximate
  a　like　result。
  To　confirm　the　chemical　tests　which　may　be　employed
  in　the　determination　of　the　artificial　aging　of
  ink　marks；　photographs　made　by　permitting　light　to
  transmit　through　the　paper　and　to　interfere　with　its
  rays　by　filtering　them　through　a　〃color〃　screen　containing
  orange　and　some　green；　will　indicate　the　presence
  of　a　fugitive　substance　in　the　ink；　usually　the
  〃added〃　color　employed　in　its　manufacture。
  The　process　of　bleaching　or　〃removal〃　of　ink　marks
  from　paper　is　frequently　employed　in　the　attempted
  eradication　of　words　or　figures　and　the　substitution
  of　others　on　monetary　instruments；　commonly　called
  〃raising。〃　Its　purpose　is　usually　a　criminal　one　and
  some　observations　as　to　the　modus　operandi　and　its
  chemistry　are　not　out　of　place　here。
  Ink　marks　made　with　a　compound　consisting　of　the
  combination　of　iron　and　an　infusion　of　galls　or　its