living　can　tell　it　from　pure　virgin　silver。　It　was　obtained　from　a　German
  chemist　now　dead；　he　used　it　for　unlawful　purposes　to　the　amount　of
  thousands；　and　yet　the　metal　is　so　perfect　that　he　was　never　discovered。
  It　is　all　melted　together　in　a　crucible；　here　it　is：　1/4　oz。　of　copper；　2
  oz。　of　brass；　3　oz。　of　pure　silver；　1　oz。　of　bismuth；　2　ozs。　of　saltpetre；
  2　ozs。　of　common　salt；　1　oz。　of　arsenic；　and　1　oz。　of　potash。
  165。　MOULDS　AND　DIES
  Take　copper；　zinc；　and　silver；　in　equal　proportions；　and　melt　them
  together；　and　mould　into　the　forms　you　desire；　and　bring　the　same　to　a
  nearly　white　heat；　now　lay　on　the　thing　that　you　would　take　the　impression
  of；　and　press　it　with　sufficient　force；　and　you　will　find　that　you　have　a
  perfect　and　beautiful　impression。　All　of　the　above　metals　should　be　melted
  under　a　coat　of　powdered　charcoal。
  166。　TO　SOFTEN　HORN
  To　1　lb。　of　wood　ashes；　add　2　lbs。　of　quicklime；　put　them　into　a　quart　of
  water；　let　the　whole　boil　till　reduced　to　one　third；　then　dip　a　feather
  in；　and　if；　on　drawing　it　out；　the　plume　should　come　off；　it　is　a　proof
  that　it　is　boiled　enough；　if　not；　let　it　boil　a　little　longer；　when　it　is
  settled　filter　it　off；　and　in　the　liquor　thus　strained　put　in　shavings　of
  horn；　let　them　soak　for　three　days；　and；　first　anointing　your　hands　with
  oil；　work　the　horn　into　a　mass；　and　print　or　mould　it　into　any　shape　you
  please。
  167。　TO　MAKE　MOULDS　OF　HORN
  If　you　wish　to　take　the　impression　of　any　coin；　medal；　&c。；　previously
  anoint　it　with　oil；　then　lay　the　horn　shavings　over　it　in　its　softened
  state；　when　dry　the　impression　will　be　sunk　into　the　horn；　and　this　will
  serve　as　a　mould　to　reproduce；　either　by　plaster　of　Paris；　putty　and　glue；
  or　isinglass　and　ground　egg　shells；　the　exact　resemblance　of　the　coin　or
  medal。
  168。　TO　CASE　FIGURES　IN　IMITATION　OF　IVORY
  Make　isinglass　and　strong　brandy　into　a　paste；　with　powder　of　egg　shells；
  very　finely　ground；　you　may　give　it　what　colour　you　please；　but　cast　it
  warm　into　your　mould；　which　you　previously　oil　over；　leave　the　figure　in
  the　mould　till　dry；　and　you　will　find；　on　taking　it　out；　that　it　bears　a
  very　strong　resemblance　to　ivory。
  169。　TRUE　GOLD　POWDER
  Put　some　gold　leaf；　with　a　little　honey　or　thick　gum　water；　（whenever　I
  speak　of　gum　I　mean　gum　arabic；）　into　an　earthen　mortar；　and　pound　the
  mixture　till　the　gold　is　reduced　to　very　small　particles；　then　wash　out
  the　honey　or　gum　repeatedly　with　warm　water；　and　the　gold　will　be　left
  behind　in　a　state　of　powder；　which；　when　dried；　is　fit　for　use。
  170。　TRUE　GOLD　POWDER
  Another；　and　perhaps　better　method　of　preparing　gold　powder　is　to　heat　a
  prepared　amalgam　of　gold　in　a　clean　open　crucible；　（an　amalgam　of　any
  metal　is　formed　by　a　mixture　of　quicksilver　with　that　metal）　continuing　a
  very　strong　heat　till　all　the　mercury　has　evaporated；　stirring　the　amalgam
  all　the　while　with　a　glass　rod；　when　the　mercury　has　entirely　left　the
  gold；　grind　the　remainder　in　a　Wedgewood's　mortar；　with　a　little　water；
  and　when　dried　it　will　be　fit　for　use。　The　subliming　the　mercury　is；
  however；　a　process　injurious　to　the　health。
  171。　COLOUR　HEIGHTENING　COMPOSITIONS
  For　yellow　gold；　dissolve　in　water　6　ozs。　of　saltpetre；　2　ozs。　of
  copperas；　1　oz。　of　white　vitriol；　and　1　oz。　of　alum。　If　wanted　redder；　add
  a　small　portion　of　blue　vitriol。
  172。　FOR　GREEN　GOLD
  Dissolve　in　water　a　mixture　consisting　of　1　1/2　oz。　of　saltpetre；　vitriol
  and　sal…ammoniac；　1　1/4　oz。　of　each；　and　1　oz。　verdigris。
  173。　FOR　RED　GOLD
  Take　1　1/2　oz。　of　red　ochre　in　fine　powder；　the　same　quantity　of　calcined
  verdigris；　1/2　oz。　of　calcined　borax；　and　4　oz。　of　melted　yellow　wax；　the
  verdigris　must　be　calcined；　or　else；　by　the　heat　applied　in　melting　the
  wax；　the　vinegar　becomes　so　concentrated　as　to　corrode　the　surface；　and
  make　it　appear　speckled。　These　last　three　are　colours　for　heightening
  compositions。
  174。　MOSAIC　GOLD
  Mosaic　gold；　or　aurum　mosaicum；　is　used　for　inferior　articles。　It　is
  prepared　in　the　following　manner：　1　lb。　of　tin　is　melted　in　a　crucible；
  and　1/2　lb。　of　purified　quicksilver　added　to　it；　when　this　mixture　is
  cold；　it　is　reduced　to　powder；　and　ground　with　1/2　lb。　of　sal　ammoniac；
  and　7　ozs。　of　flower　of　sulphur；　till　the　whole　is　thoroughly　mixed；　they
  are　then　calcined　in　a　mattrass；　and　the　sublimation　of　the　other
  ingredients　leaves　the　tin　converted　into　the　aurum　mosaicum；　which　is
  found　at　the　bottom　of　the　glass；　like　a　mass　of　bright　flakey　gold
  powder。　Should　any　black　or　discoloured　particles　appear；　they　must　be
  removed。　The　sal…ammoniac　used　here　must　be　very　white　and　clear；　and　the
  mercury　quite　pure　and　unadulterated。　When　a　shade　of　deeper　red　is
  required；　it　can　easily　be　obtained　by　grinding　a　very　small　quantity　of
  red　lead　along　with　the　above　materials。
  175。　DUTCH　OR　GERMAN　GOLD
  A　gilding　powder　is　sometimes　made　from　Dutch　gold；　which　is　sold　in　books
  at　a　very　low　price。　This　is　treated　in　the　same　way　as　the　real　gold　leaf
  in　making　the　true　gold　powder。　It　is　necessary；　when　this　inferior　powder
  is　used；　to　cover　the　gilding　with　a　coat　of　clear　varnish；　otherwise　it
  soon　loses　its　metallic　appearance。　The　same　remark　applies；　though　to　a
  less　degree；　to　Mosaic　gilding。
  176。　COPPER　POWDER
  This　is　prepared　by　dissolving　filings　or　slips　of　copper　with　nitrous
  acid　in　a　receiver。　When　the　acid　is　saturated；　the　slips　are　to　be
  removed；　or；　if　filings　be　employed；　the　solution　is　to　be　poured　off　from
  what　remains　undissolved；　small　bars　are　then　put　in；　which　will
  precipitate　the　copper　from　the　saturated　acid；　in　a　powder　of　the
  peculiar　appearance　and　colour　of　copper；　and　the　liquid　being　poured　from
  the　powder；　this　is　to　be　washed　clean　of　the　crystals　by　repeated
  levigations。
  177。　COMMON　SIZE
  The　size　used　by　painters　for　most　sorts　of　common　work　is　prepared　by
  boiling　in　water　pieces　of　parchment；　and　of　the　skins　of　animals　and　fins
  of　fish；　and　evaporating　the　solution　to　a　proper　consistency。　It　only
  differs；　however；　from　a　solution　of　glue　containing　fewer　foreign
  ingredients；　and　in　not　being　so　strong。
  178。　DR。　JOHN'S　VARNISH　FOR　PLASTER　OF　PARIS　CASTS
  Take　of　white　soap　and　white　wax；　each　half　an　ounce；　of　water　two　pints；
  boil　them　together　for　a　short　time　in　a　clean　vessel。　This　varnish　is　to
  be　applied　when　cold；　by　means　of　a　soft　brush。　It　does　not　sink　in；　it
  readily　dries；　and　its　effect　may　be　heightened　by　lightly　using　a　silk
  pocket　handkerchief。
  179。　GENERAL　DIRECTIONS　FOR　BRONZING
  This　art　is　nothing　but　a　species　of　painting；　but　far　from　being　of　the
  most　delicate　kind。　The　principal　ingredients　made　use　of　in　it　are　the
  true　gold　powder；　the　German　gold；　the　aurum　mosaicum；　and　copper　powder；
  （all　above　described。）　The　choice　of　these　powders　is；　of　course；　to　be
  determined　by　the　degree　of　brilliancy　you　wish　to　obtain。　The　powder　is
  mixed　with　strong　gum　water　or　isinglass；　and　laid　on　with　a　brush　or
  pencil；　and　when　not　so　dry　as　to　have　still　a　certain　clamminess；　a　piece
  of　soft　leather　wrapped　round　the　finger；　is　dipped　in　the　powder　and
  rubbed　over　the　work；　when　the　work　has　been　all　covered　with　the　bronze；
  it　must　be　left　to　dry；　and　any　loose　powder　then　cleared　away　by　a　hair
  pencil。
  180。　BRONZING　IN　WOOD
  This　may　be　effected　by　a　process　somewhat　differing　from　the　above；
  Prussian　blue；　patent　yellow；　raw　amber；　lamp…black；　and　pipe　clay　are
  ground　separately　with　water　on　a　stone；　and　as　much　of　them　as　will　make
  a　good　colour　put　into　a　small　vessel　three…fourths　full　of　size。　This
  mixture　is　found　to　succeed　best　on　using　about　half　as　much　more　pipe
  clay　as　of　any　of　the　other　ingredients。　The　wood　being　previously　cleaned
  and　smoothed；　and　coated　with　a　mixture　of　clean　size　and　lamp…black；
  receives　a　new　coating　with　the　above　compound　twice　successively；　having
  allowed　the　first　to　dry。　Afterwards　the　bronze　powder　is　to　be　laid　on
  with　a　pencil；　and　the　whole　burnished　or　cleaned　anew；　observing　to
  repair　the　parts　which　may　be　injured　by　this　operation；　next；　the　work
  must　be　coated　over　with　a　thin　lather　of　castile　soap；　which　will　take
  off　the　glare　of　the　burnishing；　and　afterwards　be　carefully　rubbed　with　a
  woollen　cloth。　The　superfluous　powder　may　be　rubbed　off　when　dry。
  181。　IN　BRONZING　IRON
  The　subject　should　be　heated　to　a　greater　degree　than　the　hand　can　bear；
  and　German　gold；　mixed　with　a　small　quantity　of　spirit　of　wine　varnish；
  spread　over　it　with　a　pencil；　should　the　iron　be　already　polished；　you
  must　heat　it　well　and　moisten　it　with　a　linen　rag　dipped　in　vinegar。
  182。　BRONZING　CASTS　OF　PLASTER　OF　PARIS
  There　is　a　method　of　bronzing　casts　of　plaster　of　Paris　analogous　to　that
  which　we　have　ab