american hand book of the daguerreotype-第19部分

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l；　of　common　size；　nearly　full　with　water；　add　about　quarter　of　an　ounce　of　sulphuric　acid。　　Mix　this　well；　and　let　it　stand　for　about　three　hours；　or　until　the　action　of　the　battery　becomes　weak；　when　it　is　in　order　to　work　with　a　very　uniform　action。　　Put　one　pound　of　sulphate　of　copper　in　one　quart　of　water；　stir　it　until　the　sulphate　of　copper　is　all　dissolved；　and　then　add　one　half　ounce　of　sulphuric　acid　and　a　quarter　of　an　ounce　of　nitric　acid。　This　solution；　well　mixed；　should　be　filtered；　and　it　is　ready　for　use。　It　is　very　important　that　the　solution　should　be　kept　clean；　clear；　and　free　from　all　foreign　substance。　　The　above　quantity　of　this　solution　will　be　found　sufficient　for　electrotyping　a　dozen　of　the　sixth…size　plates。　When　it　is　required　to　be　strengthened；　it　is　only　necessary　to　add　a　little　of　the　sulphate　of　copper。

〃With　the　battery　prepared　as　above；　and　the　solution　of　sulphate　of　copper　in　a　vessel　of　proper　dimensions　to　receive　your　plate；　connect　the　galvanic　current；　and　immerse　the　impressioned　plate；　letting　it　remain　until　a　thin　film　of　copper　has　been　formed；　then　the　battery　can　be　strengthened；　and　the　impression　will　be　of　sufficient　thickness　to　be　removed　in　from　eight　to　twelve　hours。　An　old　Daguerreotype　plate　attached　to　the　opposite　pole　of　the　battery　（copper　side　towards　the　face　of　the　plate　to　be　electrotyped）；　will　answer　the　same　purpose　as　the　silver…plate。

〃The　great　difficulty　in　taking　an　electrotype　impression；　and　preserving　the　original；　has　been　attributed　to　the　battery　being　too　powerful。　I　am　led　to　believe　from　practice　that　the　principal　difficulty　has　been　in　the　Daguerreotype　plate　itself；　for　if　we　use　an　impression　that　has　been　taken　but　a　few　days；　and　taken　in　the　usual　way；　we　will　find　it　difficult　to　succeed　without　spoiling　both　the　copy　and　original；　and　so　also　with　an　old　impression。

〃I　have　found　the　most　certain　method　to　be　as　follows：　Coat　the　Daguerreotype　plate　as　usual；　except　use　less　of　the　accelerators；　the　proportion　of　iodine　coating　being　greater；　of　course　the　time　of　exposure　in　the　camera　will　be　lengthened。　Mercurialize　it　at　about　a　temperature　requiring　to　develop　the　image；　from　six　to　eight　minutes；　at　least。　　Gilding　the　Daguerreotype　has　much　to　do　towards　producing　a　good　electrotype　copy。　This　should　be　done　by　applying　a　little　heat；　and　gilding　very　slowly；　giving　a　coating　of　gold　with　the　greatest　possible　uniformity。　By　this　method；　I　have　been　enabled　to　produce　any　number　of　proofs。　I　have　produced　a　dozen　from　one　impression；　and　it　remains　as　perfect　as　when　first　taken。

〃By　a　little　judgment　and　care　the　operator　will　be　enabled　to　produce　the　electrotype　copy　of　the　Daguerreotype　plate　without　any　difficulty。　The　electrotype　copy　should　be　immediately　put　under　a　glass　and　sealed　in　the　same　manner　as　the　ordinary　Daguerreotype。〃


CRAYON　DAGUERREOTYPES。

This　process　is　patented　in　the　United　States；　by　J。　A。　Whipple；　of　Boston；　and　of　course　no　honorable　person　will　use　it　for　his　own　benefit　without　purchasing　a　right。

A　white　back…ground　is　generally　employed；　the　object　being　to　blur　the　lower　portion　of　the　plate；　leaving　the　head　of　the　subject　in　relief。　Every　Daguerreotypist　is　familiar　with　the　fact　that　a　motion　of　any　body　between　the　camera　and　the　sitter　will　cause　a　〃blur。〃　Cut　a　piece　of　thin　paper　and　scallop　it；　making　a　semicircle。　This　is　kept　straight　by　means　of　a　wire　frame；　and　it　is　to　be　moved　in　front　of　the　lower　part　of　the　body　of　the　sitter　during　the　time　of　exposure　of　the　plate　in　the　camera。　　Develop　over　mercury　as　usual；　and　the　result　will　be　a　crayon　Daguerreotype。

Another　method　is　to　have　a　wheel　with　a　hole　cut　through　it　of　a　diameter　of　about　12　inches。　　This　hole　is　so　cut　as　to　leave　teeth　resembling　those　of　a　large　saw。　This　wheel　is　so　arranged　that　it　can　be　turned　around；　which　should　be　done　during　the　time　of　exposure　in　the　camera。　It　must　be　placed　between　the　camera　and　the　sitter；　and　at　such　a　distance　from　the　camera　as　to　allow　such　proportion　of　the　body　of　the　sitter　be　seen　upon　the　ground…glass　as　is　desired。　It　will　be　readily　seen　that　by　turning　this　wheel　during　the　operation　will　produce　the　same　result　as　the　paper　being　moved　in　the　other　method。　　The　teeth　make　the　〃blur。〃　The　side　of　the　wheel　towards　the　camera　may　be　black；　by　which　means　the　result　will　be　a　dark　instead　of　a　light　border。


ILLUMINATED　DAGUERREOTYPES。

This　process　is　also　patented；　and　the　remarks　on　the　preceding　subject　will　apply　in　this　case。　　The　plate　is　prepared　and　exposed　as　in　the　usual　method　of　the　Daguerreotype。　　A　white　back…ground　is　employed。　Let　the　head　of　the　sitter　come　in　the　middle　of　the　plate；　and　before　exposing　it　to　the　vapors　of　mercury；　put　a　small　mat　or　diaphragm；　having　a　small　hole　through　it；　over　or　directly　on　the　surface　of　the　plate。　This　diaphragm　should　be　bevelled；　and　the　bevel　should　be　towards　the　surface　of　the　plate；　this；　in　order　to　prevent　too　sharp　a　line　on　the　impression。　It　will　be　readily　seen　that　if　an　impressioned　plate　so　covered　is　placed　over　the　mercury；　it　will　be　developed　on　such　portions　only　as　are　exposed。　The　principle　is　so　familiar　that　further　explanations　are　unnecessary。


NATURAL　COLORS　IN　HELIOGRAPHY。

This　subject　is　worthy　the　attention　of　every　operator。　　The　following　process　is　so　plain　and　easy　of　trial　that　any　Daguerreotypist　can　try　it。　This　is　as　given　by　Mr。　James　Campbell；　and　was　published　in　Humphrey's　Journal　of　the　Daguerreotype　and　Photographic　Arts；　vol。　　5；　page　11。　Mr。　Campbell　has　done　much　to　further　the　process　announced　by　M。　Neipce；　and　his　experiments　have　proved　highly　successful。

The　following　is　submitted　as　worthy　of　trial：

〃The　proper　preparation　of　the　chloridated　plate；　to　enable　it　to　receive　colored　impressions　is　an　object　of　the　first　importance　to　those　wishing　to　experiment　on　it；　and　consequently　requires　particular　notice。　The　plate　may　be　prepared　by　making　it　the　positive　pole　of　a　battery；　and　letting　it　at　the　same　time　be　immersed　in　chlorine　water。　The　negative　pole　should　be　a　slip　of　platinum。　　All　the　colors　may　be　produced　from　a　plate　so　prepared　if　the　chlorine　and　water　are　in　the　right　proportions；　but　generally　one　color　or　the　other　predominates；　according　to　the　amount　of　chlorine　in　the　liquid。　　By　adding　the　chlorides　of　strontian；　uranium；　potassium；　sodium；　iron；　or　copper　to　the　liquid；　various　effects　may　be　produced；　and　these　bodies　will　be　found　to　produce　the　same　color　on　the　plate　that　their　flame　gives　to　alcohol。

〃The　honor　of　this　discovery　is　due　to　M。　Neipce。　Copper　gives　a　variegated　flame；　hence　many　colors　may　be　impressed　on　a　plate　prepared　with　a　solution　of　its　chloride。

〃M。　Neipce　recommends　a　solution　of　the　mixed　chlorides　of　copper　and　iron；　and　it　is　with　these；　that　I　have　been　most　successful。　As　the　chlorides　of　copper　and　iron　are　not　much　used　in　the　arts；　they　are　not　generally　found　for　sale　in　the　shops；　and　it　may　be　well　to　furnish　those　not　much　versed　in　chemistry　with　an　easy　method　of　preparing　them。

〃They　may　be　made　directly　from　either　metal　by　dissolving　it　in　hydrochloric　acid；　but　they　may　be　formed　by　a　cheaper　method；　and　by　which　also　the　acid　fumes　are　avoided。

〃Sulphate　of　iron　or　copper；　or　both　together；　may　be　dissolved　in　water　and　then　neutralized　with　common　crude　potash；　or　its　carbonate　or　bicarbonateknown　commonly　as　pearlash　and　saleratus。　If　either　of　the　latter　be　used；　there　will　be　formed　sulphate　of　potash　and　a　carbonate　of　the　metal　used；　and　there　will　also　be　a　considerable　effervescence　of　carbonic　acid；　which　will；　if　care　is　not　taken；　cause　the　mixture　to　run　over　the　vessel。　After　the　copper　or　iron　salt　is　neutralized；　which　is　known　by　its　ceasing　to　effervesce；　the　carbonate　of　the　metal　will　settle　slowly；　and　will　at　first　nearly　fill　the　vessel。　The　supernatant　fluid；　which　is　sulphate　of　potash　in　solution；　may　now　be　carefully　poured　off；　and　its　place　filled　with　water；　this　operation　should　be　repeated　several　times　until　the　water　which　passes　off　is　tasteless。　　The　carbonate　of　the　metal　rapidly　changes　to　an　oxide　by　contact　with　the　air；　and　it　will　generally　be　found；　when　it　is　sufficiently　washed；　that　it　is　at　least　half　oxide。　On　adding　hydrochloric　acid　cautiously　to　the　mixture；　a　chloric　of　the　metal　will　be　formed；　and　carbonic　acid　will　be　evolved　from　the　remaining　carbonate。　　The　chloride　formed　is　soluble；　but　as　there　are　two　chlorides　of　these　metals；　and　we　wish　to　produce　the　one　which　contains　the　most　chlorine；　it　is　best　to　add　the　acid　cautiously　until　the　solution　is　decidedly　acid。　After　filtering　the　solution；　it　is　fit　for　use；　and　it　should　be　preserved　in　well…stoppered　bottles。　　The　water　used　should　be　rain　or　distilled　water。

〃About　one　part　of　the　mixed　chlorides　should　be　used　to　three　or　four　of　water。

〃The　battery　may　be　either　Smee's；　Daniell's；　or　Grove's；　if　of　either　of　the　former；　it　should　be　of　two　series；　if　of　the　latter；　one　cup　is　sufficient。

〃The　plate　on　being　immersed　in　the　liquid；　almost　instantly　takes　a　violet　color。　　It　should　be　allowed　to　remain　from　two　to　five　minutes；　according　to　the　strength　of　the　battery；　and　until　it　becomes　nearly　black。　It　should　now　be　carefully　washed；　and　afterwards　heated　over　a　spirit　lamp　until　it　takes　a　cherry…red　color；　and　it　is　then　ready　for　exposure　in　the　camera。　　Before　speaking　of　exposing　the　plate；　it　may　be　well　to　speak　of　some　difficulties　which　the　inexperienced　operator　may　find　in　preparing　it。　　If　the　battery　is　not　in　good　order；　and　a　sufficient　current　is　not　passed　through　the　solution；　the　plate　will　become　coated　and　apparently　almost　as　well　as　when　the　battery　is　working　well　but　on　exposure　it　will　give　a　negative　picture；　and　but　little　colored；　while　if　the　battery　is　in　good　order；　the　impression　is　invariably　positive。

〃Sometimes　on　heating　the　plate　after　washing；　the　surface　is　covered　with　spots　or　assumes　a　variegated　appearance。　This　indicates　that　the　solution　is　impure；　or　that　the　plate　have　not　been　thoroughly　washed　and　are　still　contaminated　with　the　soluble　chlorides　which　ar