and　lampblack　ad　libitum。　Boil　the　whole
  again　in　a　covered　vessel；　and　stir　the　fluid　well　to
  effect　the　complete　solution　and　admixture　of　the
  gum　arabic。　Stir　it　occasionally　while　it　is　cooling；
  and　after　it　has　remained　undisturbed　for　two
  or　three　hours；　that　the　excess　of　indigo　and　lamp…
  black　may　subside；　bottle　it　for　use。　The　above
  ink　for　documentary　purposes　is　invaluable；　being
  under　all　ordinary　circumstances；　indestructible。
  It　is　also　particularly　well　adapted　for　the　use　of
  the　laboratory。　Five　drops　of　creosote　added　to　a
  pint　of　ordinary　ink　will　effectually　prevent　its　becoming
  mouldy。〃
  *　　　*　　　　*　　　　*　　　　*　　　　*　　　　*　　　　*
  〃In　November；　1854；　Mr。　Grace　Calvert　read　a
  paper　before　the　London　Society　of　Arts　in　which
  he　said　that　he　hoped　before　long　some　valuable
  dyeing　substances　other　than　carbo…azotic　acid
  would　be　prepared　from　coal　tar。
  〃In　another　paper　read　before　the　same　society
  in　1858　he　said：　'This　expectation　has　now　been
  fulfilled。　Messrs。　Perkins　and　Church　have　obtained
  several　blue　coloring　substances　from　the
  alkaloids　of　coal　tar；　and　one　from　naphthalene。'
  Also　that　himself　and　Mr。　Charles　Lowe　had　succeeded
  in　obtaining　coal　tar　products　yielding　colors
  of　a　beautiful　pink；　red；　violet；　purple；　and
  chocolate。　（These　were　not　soluble　in　water）。〃
  *　　　*　　　　*　　　　*　　　　*　　　　*　　　　*　　　　*
  〃Among　vegetable　substances　useful　in　the　arts
  is　one　that　has　long　been　known　in　New　Grenada
  under　the　name　of　the　ink…plant；　as　furnishing　a
  juice　which　can　be　used　in　writing　without　previous
  preparation。　Characters　traced　with　this　substance
  have　a　reddish　color　at　first；　which　turns　to　a　deep
  black　in　a　few　hours。　This　juice　is　said　to　be
  really　less　liable　to　thicken　than　ordinary　ink；　and
  not　to　corrode　steel　pens。　It　resists　the　action　of
  water；　and　is　practically　indelible。　The　plant　is
  known　as　coryaria　thymifolia。〃
  *　　　*　　　　*　　　　*　　　　*　　　　*　　　　*　　　　*
  〃Desormeaux　recommends　that　the　sulphate　of
  iron　be　calcined　to　whiteness；　coarse　brown　sugar
  instead　of　sugar　candy；　1/4　oz。　acetate　of　copper；
  instead　of　one　ounce　of　the　sulphate；　and　a　drop
  or　two　of　creosote　or　essential　oil　of　cloves　to　prevent
  moulding。〃　（See　Ribaucourt　receipt；　p。　194。）
  *　　　*　　　　*　　　　*　　　　*　　　　*　　　　*　　　　*
  〃Mr。　John　Spiller　communicated　to　the　London
  Chemical　News　（1861）　a　paper　on　the　employment
  of　carbon　as　a　means　of　permanent　record。　The
  imperishable　nature　of　carbon；　in　its　various　forms
  of　lamp…black；　ivory…black；　wood…charcoal；　and
  graphite　or　black　lead；　holds　out　much　greater
  promise　of　being　usefully　employed　in　the　manufacture
  of　a　permanent　writing　material；　since；　for
  this　substance；　in　its　elementary　condition　and　at
  ordinary　temperatures；　there　exists　no　solvent　nor
  chemical　reagent　capable　of　affecting　its　alteration。
  〃The　suggestion　relative　to　the　mode　of　applying
  carbon　to　these　purposes；　which　it　is　intended
  more　particularly　now　to　enunciate；　depends　on
  the　fact　of　the　separation　of　carbon　from　organic
  compounds　rich　in　that　element；　sugar；　gum；　etc。；
  by　the　combined　operation　of　heat　and　of　chemical
  reagents；　such　as　sulphuric　and　phosphoric　acids；
  which　exert　a　decomposing　action　in　the　same
  direction；　and　by　such　means　to　effect　the　deposition
  of　the　carbon　within　the　pores　of　the
  paper　by　a　process　of　development　to　be　performed
  after　the　fluid　writing　ink　has　been　to　a　certain
  extent　absorbed　into　its　substancea　system　of
  formation　by　which　a　considerable　amount　of　resistance；
  both　to　chemical　and　external　influences；
  appears　to　be　secured。　An　ink　of　the　following
  composition　has　been　made　the　subject　of　experiment：
  〃Concentrated　sulphuric　acid；
  deeply　colored　with　indigo　。。。。。。。。。。　1　fluid　ounce。
  Water；　。。。。。。。。。。。。。。。。。。。。。。。。。。。。。。　6　　　〃　　　　〃
  Loaf　Sugar；。。。。。。。。。。。。。。。。。。。。。。。。。。　1　ounce；　troy。
  Strong　mucilage　of　gum…arabic
  2　to　3　fluid　ounces。
  〃Writing　traced　with　a　quill　or　gold　pen　dipped
  in　this　ink　dries　to　a　pale　blue　color；　but　if　now　a
  heated　iron　be　passed　over　its　surface；　or　the　page
  of　manuscript　be　held　near　a　fire；　the　writing　will
  quickly　assume　a　jet　black　appearance；　resulting
  from　the　carbonization　of　the　sugar　by　a　warm
  acid；　and　will　have　become　so　firmly　engrafted
  into　the　substance　of　the　paper　as　to　oppose　considerable
  difficulty　to　its　removal　or　erasure　by　a
  knife。　On　account　of　the　depth　to　which　the
  written　characters　usually　penetrate；　the　sheets　of
  paper　selected　for　use　should　be　of　the　thickest
  make；　and　good　white　cartridge　paper；　or　that
  known　as　'cream　laid；'　preferred　to　such　as　are
  colored　blue　with　ultramarine；　for；　in　the　latter
  case；　a　bleached　halo　is　frequently　perceptible
  around　the　outlines　of　the　letters；　indicating　the
  partial　destruction　of　the　coloring　matter　by　the
  lateral　action　of　the　acid。
  〃The　writing　produced　in　this　manner　seems　indelible；
  it　resists　the　action　of　〃salts　of　lemon；〃
  and　of　oxalic；　tartaric；　and　diluted　hydrochloric
  acids；　agents　which　render　nearly　illegible　the　traces
  of　ordinary　black　writing　ink；　neither　do　alkaline
  solutions　exert　any　appreciable　action　on　the　carbon
  ink。　This　material　possesses；　therefore；　many
  advantageous　qualities　which　would　recommend　its
  adoption　in　cases　where　the　question　of　permanence
  is　of　paramount　importance。　But　it　must；　on　the
  other　hand；　be　allowed　that　such　an　ink；　in　its
  present　form；　would　but　inefficiently　fulfil　many　of
  the　requirements　necessary　to　bring　it　into　common
  use。　The　peculiar　method　of　development　rendering
  the　application　of　heat　imperative；　and　that　of
  a　temperature　somewhat　above　the　boiling　point　of
  water；　together　with　the　circumstance　that　it　will
  be　found　impossible　with　a　thin　sheet　of　paper　to
  write　on　both　sides；　must　certainly　be　counted
  among　its　more　prominent　disadvantages。〃
  *　　　*　　　　*　　　　*　　　　*　　　　*　　　　*　　　　*
  〃Fire…proof　ink　for　writing　or　printing　on
  incombustible　paper　is　made　according　to　the　following
  recipe：　Graphite；　finely　ground；　22　drams；
  copal　or　other　resinous　gum；　12　grains；　sulphate
  of　iron；　2　drams；　tincture　of　nutgalls；　2　drams；
  and　sulphate　of　indigo；　8　drams。　These　substances
  are　thoroughly　mixed　and　boiled　in　water；
  and　the　ink　thus　obtained　is　said　to　be　both　fire…
  proof　and　insoluble　in　water。　When　any　other
  color　but　black　is　desired；　the　graphite　is　replaced
  by　an　earthly　mineral　pigment　of　the　desired　color。〃
  *　　　*　　　　*　　　　*　　　　*　　　　*　　　　*　　　　*
  〃Ineradicable　Writing。A　French　technical
  paper；　specially　devoted　to　the　art　and　science　of
  paper　manufacture；　states　that　any　alterations　or
  falsifications　of　writings　in　ordinary　ink　maybe　rendered
  impossible　by　passing　the　paper　upon　which
  it　is　intended　to　write　through　a　solution　of　one　milligram
  （0。01543　English　grain）　of　gallic　acid　in　as
  much　pure　distilled　water　as　will　fill　to　a　moderate
  depth　an　ordinary　soup…plate。　After　the　paper　thus
  prepared　has　become　thoroughly　dry；　it　may　be
  used　as　ordinary　paper　for　writing；　but　any　attempt
  made　to　alter；　falsify；　or　change　anything　written
  thereon；　will　be　left　perfectly　visible；　and　may　thus
  be　readily　detected。〃
  *　　　*　　　　*　　　　*　　　　*　　　　*　　　　*　　　　*
  〃Exchequer　Ink。To　40　pounds　of　galls；　add
  10　pounds　of　gum；　9　pounds　of　copperas；　and　45
  gallons　of　soft　water。　This　ink　will　endure　for
  centuries。〃
  *　　　*　　　　*　　　　*　　　　*　　　　*　　　　*　　　　*
  〃Take　of　oil　of　lavender；　120　grains；　of　copal
  in　powder；　17　grains；　red　sulphuret　of　mercury；　60
  grains。　The　oil　of　lavender　being　dissipated　with
  a　gentle　heat；　a　colour　will　be　left　on　the　paper
  surrounded　with　the　copal；　a　substance　insoluble
  in　water；　spirits；　acids；　or　alkaline　solutions。
  〃This　composition　possesses　a　permanent　colour；
  and　a　MSS。　written　with　it；　may　be　exposed　to　the
  process　commonly　used　for　restoring　the　colour　of
  printed　books；　without　injury　to　the　writing。　In
  this　manner　interpolations　with　common　ink　may
  be　removed。〃
  *　　　*　　　　*　　　　*　　　　*　　　　*　　　　*　　　　*
  Boil　parchment　slips　or　cuttings　of　glove
  leather；　in　water　till　it　forms　a　size；　which；　when
  cool；　becomes　of　the　consistence　of　jelly；　then；
  having　blackened　an　earthern　plate；　by　holding　it
  over　the　flame　of　a　candle；　mix　up　with　a　camel
  hair　pencil；　the　fine　lamp…black　thus　obtained；　with
  some　of　the　above　size；　while　the　plate　is　still
  warm。　This　black　requires　no　grinding；　and　produces
  an　ink　of　the　same　colour；　which　works　as
  fregy　with　the　pencil；　and　is　as　perfectly
  transparent　as　the　best　Indian　ink。〃
  *　　　*　　　　*　　　　*　　　　*　　　　*　　　　*　　　　*
  〃Instead　of　water　use　brandy；　with　the　same
  ingredients　which　enter　into　the　composition　of
  any　ink；　and　it　will　never　freeze。〃
  *　　　*　　　　*　　　　*　　　　*　　　　*　　　　*　　　　*
  〃Bacteria　in　InkAccording　to　experiments
  which　have　recently　been　completed　at　Berlin　and