kept：　and　perhaps　more　gum　was　used　in　them；
  or　possible　they　were　washed　over　with　some　kind
  of　varnish；　though　not　such　as　gave　gloss。
  〃One　of　the　specimens　sent　me　by　Mr。　Astle；
  of　the　fifteenth　century；　and　the　letters　were　those
  of　an　engrossing　hand；　angular；　without　any　FINE
  strokes；　broad　and　very　black。　On　this　none　of
  the　above…mentioned　re…agents　produced　any　considerable
  effect；　most　of　them　seemed　to　make　the
  letters　blacker；　probably　by　cleaning　the　surface；
  and　the　acids；　after　having　been　rubbed　strongly　on
  the　letters；　did　not　strike　any　deeper　tinge　with　the
  phlogisticated　alkali。　Nothing　had　a　sensible　effect
  toward　obliterating　these　letters　but　what　took　off
  part　of　the　surface　of　the　vellum；　when　small　rolls；
  as　of　a　dirty　matter；　were　to　be　perceived。　It　is
  therefore　unquestionable；　that　no　iron　was　used　in
  this　ink；　and　from　its　resistance　to　the　chemical
  solvents；　as　well　as　a　certain　clotted　appearance　in
  the　letters　when　examined　closely；　and　in　some
  places　a　slight　degree　of　gloss；　I　have　little　doubt
  but　they　were　formed　with　a　composition　of　a　black；
  sooty　or　carbonaceous　powder　and　oil；　probably
  something　like　our　present　printer's　ink；　and　am　not
  without　suspicion　that　they　were　actually　printed
  （a　subsequent　examination　of　a　larger　portion　of
  this　supposed　MSS。　has　shown　that　it　is　really　a　part
  of　a　very　ancient　printed　book）。
  〃Whilst　I　was　considering　of　the　experiments
  to　be　made；　in　order　to　ascertain　the　composition
  of　ancient　inks；　it　occurred　to　me　that　perhaps　one
  of　the　best　methods　of　restoring　legibility　to　decayed
  writing　might　be　to　join　phlogisticated　alkali
  with　the　remaining　calx　of　iron；　because；　as　the
  quantity　of　precipitate　formed　by　these　two　substances
  very　much　exceeds　that　of　the　iron　alone；
  the　bulk　of　the　colouring　matter　would　thereby　be
  greatly　augmented。　M。　Bergman　was　of　opinion
  that　the　blue　precipitate　contains　only　between　a
  fifth　and　a　sixth　part　of　its　weight　of　iron；　and
  though　subsequent　experiments　tend　to　show　that；
  in　some　cases　at　least；　the　proportion　of　iron　is
  much　greater；　yet　upon　the　whole　it　is　certainly
  true；　that　if　the　iron　left　by　the　stroke　of　a　pen
  were　joined　to　the　colouring　matter　of　phlogisticated
  alkali；　the　quantity　of　Prussian　blue　thence
  resulting　would　be　much　greater　than　the　quantity
  of　black　matter　originally　contained　in　the　ink
  deposited　by　the　pen；　though　perhaps　the　body　of
  colour　might　not　be　equally　augmented。　To　bring
  the　idea　to　the　test；　I　made　a　few　experiments　as
  follows：
  〃The　phlogisticated　alkali　was　rubbed　upon　the
  bare　writing　in　different　quantities；　but　in　general
  with　little　effect。　In　a　few　instances；　however；　it
  gave　a　bluish　tinge　to　the　letters；　and　increased
  their　intensity；　probably　where　something　of　an
  acid　nature　had　contributed　to　the　diminution　of
  their　colour。
  〃Reflecting　that　when　phlogisticated　alkali　forms
  its　blue　precipitate　with　iron　the　metal　is　first　usually
  dissolved　in　an　acid；　I　was　next　induced　to　try　the
  effect　of　adding　a　dilute　mineral　acid　to　writing　besides
  the　alkali。　This　answered　fully　to　my　expectations；
  the　letters　changing　very　speedily　to　a　deep
  blue　colour；　of　great　beauty　and　intensity。
  〃It　seems　of　little　consequence　as　to　the　strength
  of　colour　obtained；　whether　the　writing　be　first　wetted
  with　the　acid；　and　then　the　phlogisticated　alkali　be
  touched　upon　it；　or　whether　the　process　be　inverted；
  beginning　with　the　alkali；　but　on　another　account
  I　think　the　latter　way　preferable。　For　the　principal
  inconvenience　which　occurs　in　the　proposed
  method　of　restoring　MSS。　is；　that　the　colour　frequently
  spreads；　and　so　much　blots　the　parchment
  as　to　detract　greatly　from　the　legibility；　now　this
  appears　to　happen　in　a　less　degree　when　the　alkali
  is　put　on　first；　and　the　dilute　acid　is　added　upon　it。
  〃The　method　I　have　hitherto　found　to　answer
  best　has　been　to　spread　the　alkali　thin　with　a
  feather　or　a　bit　of　stick　cut　to　a　blunt　point；　though
  the　alkali　has　occasioned　no　sensible　change　of
  colour；　yet　the　moment　that　the　acid　comes　upon　it；
  every　trace　of　a　letter　turns　at　once　to　a　fine　blue；
  which　soon　acquires　its　full　intensity；　and　is　beyond
  comparison　stronger　than　the　colour　of　the　original
  trace　had　been。　If　now　the　corner　of　a　bit　of　blotting
  paper　be　carefully　and　dexterously　applied
  near　the　letters；　in　order　to　suck　up　the　superfluous
  liquor；　the　staining　of　the　parchment　may　be　in　a
  great　measure　avoided：　for　it　is　this　superfluous
  liquor　which　absorbing　part　of　the　colouring　matter
  from　the　letters　becomes　a　dye　to　whatever　it　touches。
  Care　must　be　taken　not　to　bring　the　blotting　paper
  in　contact　with　the　letters；　because　the　colouring
  matter　is　soft　whilst　wet；　and　may　easily　be　rubbed
  off。　The　acid　I　have　chiefly　employed　has　been
  the　marine；　but　both　the　vitriolic　and　nitrous　succeed
  very　well。　They　should　undoubtedly　be　so
  far　diluted　as　not　to　be　in　danger　of　corroding　the
  parchment；　after　which　the　degree　of　strength　does
  not　seem　to　be　a　matter　of　much　nicety。
  〃The　method　now　commonly　practiced　to　restore
  old　writings；　is　by　wetting　them　with　an　infusion
  of　galls　in　white　wine。〃
  （See　a　complicated　process　for　the　preparation　of
  such　a　liquor　in　Caneparius　De　Atramentis；　A。　D。
  1660；　p。　277）
  〃This　certainly　has　a　great　effect；　but　is　subject；
  in　some　degree；　to　the　same　inconvenience　as　the
  phlogisticated　alkali；　of　staining　the　substance　on
  which　the　writing　was　made。　Perhaps　if；　instead
  of　galls　themselves；　the　peculiar　acid　of　or　other
  matter　which　strikes　the　black　with　iron　were　separated
  from　the　simple　astringent　matter；　for　which
  purpose　two　different　processes　are　given　by　Piesenbring
  and　by　Scheele；　this　inconvenience　might
  be　avoided。　It　is　not　improbable；　likewise；　that　a
  phlogisticated　alkali　might　be　prepared　better　suited
  to　this　object　than　the　common；　as　by　rendering　it
  as　free　as　possible　from　iron；　diluting　it　to　a　certain
  degree；　or　substituting　the　volatile　alkali　for　the
  fixed。　Experiment　would　most　likely　point　out
  many　other　means　of　improving　the　process　described
  above；　but　in　its　present　state　I　hope　it
  may　be　of　some　use；　as　it　not　only　brings　out　a
  prodigious　body　of　colour　upon　letters　which　were
  before　so　pale　as　to　be　almost　invisible；　but　has
  the　further　advantages　over　the　infusions　of　galls；
  that　it　produces　its　effect　immediately；　and　can　be
  confined　to　these　letters　only　for　which　such　assistance
  is　wanted。〃
  The　Society　of　Arts　in　1830；　received　a　communication
  from　Dr。　Bostock；　in　the　course　of　which　he
  stated　that　the　〃tannin；　mucilage　and　extractive
  matter　are　without　doubt　the　principal　causes　of　the
  difficulty　which　is　encountered　in　the　formation　of　a
  perfect　and　durable　ink　and　for　a　good　ink　the　essential
  ingredients　are　gallic　acid　and　a　sesqui　salt　of
  iron。〃　Owing　to　his　working　with　galls　he　was　unable
  to　make　decisive　experiments；　but　he　concludes；
  and　that　rightly；　that　in　proportion　as　ink　consists
  merely　of　gallate　of　iron；　it　is　less　liable　to　decomposition
  and　any　kind　of　metamorphosis。
  In　1831　the　Academy　of　Sciences　in　France　took
  up　the　matter　and　designated　a　committee　composed
  of　chemists　with　instructions　to　study　the　subject　of　a
  permanent　ink。　After　long　research　it　reported　that
  it　was　unable　to　recommend　any　better　ink　than　the
  tanno…gallate　of　iron　one　then　in　use；　but　〃it　should
  be　properly　compounded。〃
  Peddington　investigated；　1841…48；　the　ancient　MSS。
  collected　by　the　Asiatic　Society　of　Bengal；　Calcutta；
  and　published　the　results　in　〃Examination　of　Some
  Decayed　Oriental　Works　in　the　Library　of　the　Asiatic
  Society；〃　which　are　of　much　interest　as　relating　to
  〃mineral〃　inks；　the　〃gall〃　inks　being　unknown　in
  Asia　after　the　twelfth　century。
  Up　to　thirty…five　years　ago；　the　manufacture　of
  〃gall〃　inks　necessitated　a　complicated　series　of　processes
  and　long　periods　of　time　to　enable　the　ink　to
  settle　properly；　etc。　It　was　Professor　Penny　of　the
  Anderson　University　who　suggested　the　way　to　avoid
  one　of　the　processes　pertaining　to　ink…making　by
  utilizing　the　known　fact；　that　tannin　is　more　soluble
  in　cold　than　in　warm　or　hot　water。　It　was　adopted
  all　over　the　world　and　revolutionized　the　manufacture
  of　ink；　by　doing　away　with　boiling　processes　and　hot
  macerations　of　ingredients。　With　hardly　in　exception
  the　best　tanno…gallate　of　iron　（〃gall〃）　inks　are
  now　〃cold〃　made。
  CHAPTER　XIII。
  STUDY　OF　INK。
  INVESTIGATIONS　BY　STARK　OF　INK　QUALITIES　COVERING
  A　PERIOD　OF　TWENTY…THREE　YEARSABSTRACT　FROM
  HIS　REPORT　OF　1855DR。　CHILTON　EXPERIMENTS　IN
  NEW　YORK　CITY　1856ACTION　OF　THE　PRUSSIAN
  GOVERNMENT　IN　1859　AND　EMPLOYMENT　OF　AN　OFFICIAL
  INKWATTENBACH'S　GERMAN　TREATISE　ON　THE
  ARCHIVES　OF　THE　MIDDLE　AGESWILLIAM　INGLIS
  CLARK　ATTEMPTS　TO　PL