american hand book of the daguerreotype-第3部分

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ays　of　light。　　It　is　this　nicely…balanced　combination　which　ensures；　in　the　highest　degree；　a　union　of　the　essential　qualities　of　a　fine　Daguerreotype；　viz。；　clearness　and　strength；　with　softness　and　purity　of　tone。

〃So　far　as　I　know；　it　is　the　universal　practice　of　operators　to　judge　of　the　proportion　of　iodine　and　bromine　in　coating　the　plate；　by　two　standards　of　color　the　one　fixed　upon　for　the　iodine；　the　other　for　the　additional　coating　of　bromine。　Now　I　maintain　that　these　alone　form　a　very　fallacious　standard。　first；　because　the　color　appears　to　the　eye　either　lighter　or　darker；　according　as　there　is　more　or　less　light　by　which　we　inspect　the　coating；　and　secondly；　because　if　it　occur　that　we　are　deceived　in　obtaining　the　exact　tint　for　the　first　coating；　we　are　worse　misled　in　obtaining　the　second；　for　if　the　iodine　coating　be　too　light；　then　an　undue　proportion　of　bromine　is　used　in　order　to　bring　it　to　the　second　standard；　and　vice　versa。〃

The　iodine　box　should　be　kept　clean　and　dry。　　The　plate　immediately　after　the　last　buffing；　should　be　placed　over　the　iodine；　and　the　coating　will　depend　upon　the　character　of　the　tone　of　the　impression　desired。　Coating　over　dry　iodine　to　an　orange　color；　then　over　the　accelerator；　to　a　light　rose；　and　back　over　iodine　one　sixth　as　long　as　first　coating；　will　produce　a　fine；　soft　tone；　and　is　the　coating　generally　used　for　most　accelerators。　　The　plate　iodized　to　a　dark　orange　yellow；　or　tinged　slightly　with　incipient　rose　color；　coated　over　the　accelerator　to　a　deep　rose　red；　then　back　over　iodine　one…tenth　as　long　as　at　first　coating；　gives　a　clear；　strong；　bold；　deep　impression。

I　will　here　state　a　singular　fact；　which　is　not　generally　known　to　the　operator。　　If　a　plate；　coated　over　the　iodine　to　a　rose　red；　and　then　exposed　to　strong　dry　quick　or　weak　bromine　water；　so　that　a　change　of　color　can　be　seen；　then　recoated　over　the　iodine　twice　as　long　as　at　first　coating；　it　will　be　found　far　more　sensitive　when　exposed　to　the　light　than　when　it　has　been　recoated　over　the　iodine　one…fourth　of　the　time　of　the　first　coating。

Probably　the　best　accelerating　combination　is　the　American　compound　formerly　known　as　〃Gurney's　American　compound；〃　or　some　of　the　combinations　of　bromide　of　lime。　The　first　is　thought　to　possess　perhaps　more　uniformity　in　its　action　than　any　other　combination　I　have　ever　used。

The　plate　once　coated　should　be　kept　excluded　from　the　light　by　means　of　the　plate　holder　for　the　camera　box。

I　will　notice　one　of　the　principal　causes　having　a　tendency　to　prevent　the　perfect　uniformity　of　chemical　action；　between　the　iodine　and　silver；　hydrogen；　or　the　moisture　in　the　atmosphere；　makes　a　very　perceptible　barrier。　This　moisture　may　arise　as　the　result　of　the　cold；　from　a　want　of　friction　in　the　buffing　of　the　plate；　which；　coming　in　contact　with　the　warmer　air；　as　a　writer　on　this　subject　says：

〃It　is　well　known　that　as　often　as　bodies；　when　cold；　are　exposed　to　a　warmer　air；　the　humidity　contained　in　them　is　condensed。　It　is　to　this　effect　that　we　must　attribute　the　difficulty　experienced　in　operating　in　most　cases。〃　　This　is　corroborated　by　the　results　experienced　by　our　operators。　　So　it　is　seen　that　the　plate　should　be　of　a　temperature　above　that　of　the　atmosphere。　Mr。　Gurney　submits　his　plates　to　a　gentle　heat　from　a　spirit　lamp　just　before　exposing　them　to　the　vapor　of　iodine。　Experience　has　convinced　me　that　a　plate　heated　to　about　80　deg。　before　being　exposed　to　iodine　will　present　a　far　better　defined　image　than　aplate　at　a　temperature　of　50　deg。　I　account　for　this　by　noticing　that；　at　a　higher　temperature；　the　plate　throws　off　any　larger　crystals　that　might　otherwise　be　deposited；　receiving　only　the　finer；　thus　producing　a　more　perfect　chemical　combination　of　iodide　of　silver。　I　would　call　the　attention　of　the　operator　to　this　point；　as　presenting　something　of　interest；　and　which　may　direct　in　a　way　of　accelerating　the　future　operations。

That　the　presence　of　a　film　of　moisture　over　the　plate　is　a　preventive　of　uniform　chemical　action；　may　be　readily　understood　from　the　fact　that　iodine　is　almost　insoluble　in　water；　requiring　seven　thousand　parts　of　water　to　dissolve　one　of　iodine；　or　one　grain　to　a　gallon　of　water。　Yet　its　affinities　for　silver　and　other　substances　are　so　powerful　as　to　prevent　its　existing　in　an　insulated　state；　hence　we　can　account　for　the　frequent　occurrence　of　a　plate　presenting　parts　of　an　image　over　its　surface。　It　is　quite　evident　that　those　parts　of　plate's　surface　covered　with　moisture　are　nothing　like　as　sensitive　to　the　iodine　as　those　parts　perfectly　free。

Exposure　of　the　plate　in　the　Camera；　and　Position。The　time　of　exposure　necessary　to　produce　an　image　upon　the　Daguerreotype　plate；　can　only　be　determined　by　experiment；　and　requires　a　liberality　of　judgment　to　be　exercised　on　the　part　of　the　operator。　The　constant　variation　of　the　light　renders　it　impossible　to　lay　down　any　exact　rule　upon　this　point。　　Light　is　not　alone　to　be　considered；　the　amount　of　coating　exercises　a　deviating　influence；　also　the　subjects　to　be　represented　are　not　equally　photogenic；　some　requiring　much　longer　time　of　exposure　than　others。　This　may　be　easily　observed　by　exposing　the　plate　at　the　same　time　to　a　plaster　bust　and　a　piece　of　black　velvet；　the　first　being　a　much　stronger　reflector　of　light　than　the　latter：　the　time　necessary　to　produce　a　well　developed　image　of　the　velvet　being　about　six　times　longer　than　that　required　to　produce　an　equally　defined　image　of　plaster。　The　manner　of　judging　correctly　of　the　time　is　by　the　appearance　of　impression　after　it　has　been　developed　by　the　mercurial　vapors。　Should　it　present　a　deep　blue　or　black　appearance　it　is　solarized　or　over…timed。　This　sometimes　is　to　an　extent；　that　a　perfect　negative　is　formed；　the　white　being　represented　black；　and　the　dark　light。

An　object　requiring　the　particular　care　and　attention　of　the　operator　is　the　proper　focus。　　It　is　not　unfrequently　the　complaint　of　sitters　that　their　hands　are　represented　as　being　magnified　and　greatly　out　of　proportion　with　the　general　figure。　This　is　the　case　also　with　the　nose　and　eyes；　but　in　a　less　degree。　As　this　cannot　be　wholly　remedied；　it　is　desirous　to　come　as　near　as　possible；　and　in　order　to　do　this；　it　is　necessary　to　present　the　figure　in　such　a　position　as　to　bring　it　as　nearly　as　possible　upon　the　same　plane　by　making　all　parts　nearly　at　equal　distance　from　the　lenses。　　This　must　be　done　by　the　sitter　inclining　the　head　and　bust　formed　to　a　natural；　easy　position；　and　placing　the　hands　closely　to　the　body；　thus　preserving　a　propel　proportion；　and　giving　a　lively　familiarity　to　the　general　impression。　It　is　not　an　uncommon　fault　among　our　less　experienced　operators　to　give　a　front　view　of　the　face　of　nearly　every　individual；　regardless　of　any　particular　form；　and　this　is　often　insisted　upon　by　the　sitter；*　who　seems　to　think　the　truth　of　the　picture　exists　principally　in　the　eyes　staring　the　beholder　full　in　the　face。

*　I　might　here　picture　some　curious　scenes　experienced　by　our　operators　Every　one　is　familiar　with　a　certain　class　of　our　community　whose　ideas　of　the　importance　of　a　free　and　easy　position　of　the　body　are　too　closely　confined　with　stays；　attention　to　toilet；　tightly　fitting　dress　coats　and　the　like；　to　admit　of　being　represented　as　if　nature　had　endowed　them　with　least　possible　power　of　flexibility。　To　such　we　would　suggest　the　following；　to　be　well　learned　and　retained　in　the　mind　while　presenting　themselves　before　the　Daguerreotype　camera：

〃The　experience　of　one　who　has　often　been　Daguerreotyped；　is；　to　let　the　operator　have　his　own　way。〃

Nothing；　in　many　instances；　can　be　more　out　of　place　in　a　Daguerreotype　portrait　than　this；　for　let　a　man　with　a　thin；　long；　defeated…politician…face；　be　represented　by　a　directly　front　view；　we　have；　to　all　appearances；　increased　the　width　of　the　face　to　such　an　extent　as　to　reveal　it　flat　and　broad；　losing　the　characteristic　point　by　which　it　would　be　the　most　readily　recognized。　The　method　we　should　adopt　in　taking　the　likeness　of　such　an　individual　as　above；　would　be　to　turn　the　face　from　the　camera；　so　as　to　present　the　end　of　the　nose　and　the　prominence　of　the　cheek　bone　equally　distant　from　the　lenses；　and　then　focusing　on　the　corner　of　the　eye　towards　the　nose；　we　cannot　in　many　cases；　fail　to　produce　an　image　with　the　lips；　chin；　hair；　eyes　and　forehead　in　the　minutest　possible　definition。

It　should　be　the　study　of　every　operator　to　notice　the　effect　of　the　lights　and　shades　while　arranging　the　sitter；　and　at　the　same　time　be　very　particular　to　give　ease　in　the　position。

No　matter　how　successful　the　chemical　effect　may　have　been；　should　the　image　appear　stiff　and　monument…like；　all　is　lost。　〃In　the　masterpiece；　grace　and　elegance　must　be　combined。〃

I　will　here　use　the　words　of　another；　which　are　very　true：

〃So　great　is　the　difference　in　many　faces；　when　inspected　in　opposite　directions；　that　one　of　the　two　views；　however　accurately　taken；　would　not　communicate　the　likeness　it　not　being；　the　usually　observed　characteristic　form。　When　the　right　view　of　the　head　is　obtained；　it　is　first　necessary　to　consider　the　size　of　the　plate　it　is　to　be　taken　on；　so　as　to　form　an　idea　of　the　proportion　the　head　should　bear　to　it。　The　mind　must　arrange　these　points　before　we　commence；　or　we　shall　find　everything；　too　large　or　too　small　for　the　happy　proportion　of　the　picture；　and　the　conveying　of　a　just　notion　of　the　stature。　　The　work　will　have　to　be　done　over；　and　time　sacrificed；　if　this　is　not　attended　to。　The　adjustment　of　the　head　to　the　size　of　the　plate　（as　seen　from　the　margin　of　the　mat）；　is　not　to　be　taught：　everyone　must　bring　himself；　by　scrutinizing　practice；　to　mathematical　accuracy；　for　something　will　be　discovered　in　every　face　which　can　be　surmounted　only　by　experience。

〃The　eye　nearest　the　camera；　in　a　three…quarter…face；　is　placed　in　the　middle　of　the　breadth　of　the　plate；　the　chin；　in　a　person　of　middle　stature；　in　the　middle　of　the　length；　and　higher　according　to　the　proportional　height　of　the　person。〃

In　regard　to　the　proper　elevation　of　the　camera；　it　may　be　here　stated　that　I　have　found　it　best　in　taking　portraits　where　the　hands　a