the history and practice of the art of photography-第11节

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Place　the　block　upon　the　swivle；　and　hold　it　firmly　with　the　left　hand；　take　a　small　knot　or　pellet　of　cotton；　or；　if　you　like　it　better；　a　small　piece　of　canton　flannelwet　it　with　a　little　diluted　nitric　acid；　then　sift　some　finely　prepared　rottenstoneDavie's；*　if　you　can　get　it　upon　it；　and　rub　it　over　the　plate　with　a　continual　circular　motion；　till　all　traces　of　the　dirt　and　scratches　are　removed；　then　wipe　off　the　rottenstone　with　a　clean　piece　of　cotton；　adopting；　as　before；　a　slight　circular　motion；　at　the　same　time　wiping　the　edges　of　the　plate。　Even　the　back　should　not　be　neglected；　but　throughly　cleansed　from　any　dirt　or　greasy　film　it　may　have　received　from　handling。

*　Sold　by　E。　Anthony。

When　this　is　thoroughly　accomplished；　mix　a　portion　of　your　tripoli　with　the　dilute　nitric　acid；　to　the　consistence　of　thick　cream。　Then　take　a　pellet　of　cotton　and　well　polish　the　plate　with　this　mixture；　in　the　same　manner　as　with　the　rottenstone。　　Continue　the　process　till；　on　removing　the　tripoli　with　a　clean　pellet；　the　plate　exhibits　a　clear；　smooth；　bright　surface；　free　from　all　spots；　or　scratches。　Any　remains　of　the　acid　on　the　plate　may　be　entirely　removed　By　sifting　on　it　a　little　Drying　powder；　and　then　wiping　it　carefully　off　with　a　fine　camels　hair　brush；　or　duster。　　The　finishing　polish　is　now　to　be　given。

For　this　purpose　the　rougeor　a　mixture　of　rouge　and　lamp…black；　in　the　proportion　of　one　part　of　the　former　to　seven　of　the　latteris　used。　It　should　be　kept　either　in　a　muslin　bag；　or　wide　mouth　bottle；　over　which　a　piece　of　muslin　is　tiedin　fact；　both　the　rottenstone　and　tripoli　should　be　preserved　from　the　dust　in　the　same　manner。　With　a　little　of　this　powder　spread　over　the　buffdescribed　on　page　53　the　plate　recieves　its　final　polish；　the　circular　motion　is　changed　for　a　straight　one　across　the　plate；　which；　if　intended　for　a　portrait；　should　be　buffed　the　narrow　way；　but　if；　for　a　landscape　or　view　of　a　house；　the　length　way　of　the　plate。

The　operation　of　cleaning　the　plate　at　first　appears　difficult　and　tedious；　and　many　have　been　deterred　from　attempting　this　interesting　art　on　that　account；　but；　in　reality；　it　is　more　simple　in　practice　than　in　description；　and　with　a　little　patience　and　observation；　all　difficulties　are　easily　overcome。　Great　care　must　be　taken　to　keep　the　buff　free　from　all　extraneous　matter；　and　perfectly　dry；　and　when　not　in　use　it　should　be　wrapped　up　in　tissue　paper；　or　placed　in　a　tight　box。

The　plate　should　be　buffed　immediately　before　the　sensitive　coating　is　given；　particles　of　dust　are　thus　effectually　removed；　the　temperature　of　the　plate　is　also　increased　by　the　friction；　and　the　required　tint　more　readily　obtained。

SECOND　OPERATION。Applying　the　sensative　coating。The　apparatus　and　chemicals　required；　are　an

Iodine　boxsee　fig。　14　page　53。

Bromine　boxsimilar　to　the　iodine　box　but　a　trifle　deeper。

Dry　Iodine。

Bromine；　or　a　compound　of　Bromine　and　Chloride　of　Iodine；　or　other　sensitive　mixture。

Most　of　our　best　operators　use　the　compound　Bromine　and　Chloride　of　Iodine。　　In　the　early　days　of　the　Daguerreotype；　Iodine　alone　was　used　in　preparing　the　plate；　and　although　it　still　plays　a　very　important　part；　other　preparations；　called　accelerating　liquids；　quickstuff；　&c。；　are　used；　and　the　discovery　of　which　has　alone　ensured　the　application　of　the　Daguerreotype　successfully　to　portrait　takingfor　when　first　introduced　among　us　it　took　from　five　to　ten　minutes　to　produce　a　tolerable　good　view；　while　now　but　the　fraction　of　a　minute　is　required　to　obtain　an　accurate　likeness。

To　iodize　the　plate　perfectly　it　must　be　placed　over　the　iodine　vapor　immediately　after　buffing。　　Scatter　from　a　sixteenth　to　the　eighth　of　an　ounce　of　dry　iodine　over　the　bottom　of　your　coating　box；　and　slightly　cover　it　with　cotton　wool。　　The　plate　is　then　dropped　into　the　frame　b；　fig。　12；　with　its　silvered　surface　downward；　and　thrust　under　the　lid　h。　　The　bright　surface　of　the　plate　is　soon　coated　with　a　film　of　iodine　of　a　fine　yellow　color；　it　is　then　removed　and　placed　over　the　accelerating　solution。　It　is　not　absolutely　necessary　to　perform　this　operation　in　the　dark；　although　a　bright　light　should　be　avoided。　Not　so　the　next　part　of　the　process；　viz；　giving　the　plate　its　extreme　sensitiveness；　or　coating　with　the　accelerating　liquids。　In　this　great　caution　should　be　used　to　prevent　the　slightest　ray　of　light　impringing　directly　on　the　plate；　and　in　examining　the　color　reflected　light　should　always　be　used。　A　convient　method　of　examining　the　plate；　is　to　make　a　small　hole　in　the　partition　of　the　closet　in　which　you　coat；　and　cover　it　with　a　piece　of　tissue　paper；　by　quickly　turning　the　plate　so　that　the　paper　is　reflected　upon　it　the　color　is　very　distinctly　shown。　Most　of　our　operators　are　not　so　particular　in　this　respect　as　they　should　be。

ACCELERATING　LIQUID。Of　these　there　are　several　kinds；　which　differ　both　in　composition　and　actionsome　acting　very　quickly；　others　giving　a　finer　tone　to　the　picture　although　they　are　not　so　expeditious　in　there　operations；　or　in　other　words；　not　so　sensitve　to　the　action　of　light。　　These　are　adopted　by　Daguerreotypists　according　to　their　tastes　and　predjudices。　They　are　all　applied　in　the　same　way　as　the　coating　of　iodine。　The　following　are　the　best。

Bromine　waterThis　solution　is　much　used　in　France；　and；　I　shall　therefore　give　its　preparation；　and　the　method　of　using　it；　in　the　words　of　M。　Figeau。　　〃Put　into　a　bottle　of　pure　water；　a　large　excess　of　bromine；　shake　the　mixture　well；　and　before　using　it；　let　all　the　bromine　be　taken　up。　　An　ascertained　quantity　of　this　saturated　water　is　then　diluted　in　a　given　quantity　of　distilled　water；　which　gives　a　solution　of　bromine　that　is　always　identical。〃　M。　Figeau　recommends　one　part　of　the　saturated　solution　to　thirty　parts　its　bulk　of　water；　but　M。　Lesebour　finds　it　more　manageable　if　diluted　with　forty　times。　　In　case　pure　distilled；　or　rain　water　cannot　be　procured；　a　few　drops　of　nitric　acidsay　six　to　the　quart　should　be　added　to　the　common　water。

Put　into　the　bromine　box　a　given　quantity　of　this　solution；　sufficient　to　well　cover　the　bottom；　the　plate；　having　been　iodized　to　a　deep　yellow；　is　placed　over　it；　the　time　the　plate　should　be　exposed　must　be　ascertained　by　making　a　few　trials；　it　averages　from　twelve　to　forty　seconds。　When　once　ascertained；　it　is　the　same　for　any　number　of　plates；　as　the　solution；　which　of　course　would　become　weaker　and　weaker；　is　changed　after　every　operation；　the　same　quantity　being　always　put　into　the　pot。

Chloride　of　Iodine。This　is　prepared　by　introducing　chlorine　gass　into　a　glass　vessel　containing　iodine；　the　iodine　is　liquified；　and　the　above　named　compound　is　the　result。　Operators　need　not；　however；　be　at　the　trouble　and　expense　of　preparing　it；　as　it　can　be　obtained　prefectly　pure　of　Mr。　Anthony；　205　Broadway；　N。　Y。；　as　also　all　of　the　chemicals　herein　enumerated。　The　compound　is　diluted　with　distilled　water；　and　the　plate　submitted　to　its　action　till　it　is　of　a　rose　color。　　Chloride　of　iodine　alone；　is　seldom　if　ever　used　now　by　American　operators；　as　it　does　not　sufficiently　come　up　to　their　locomotive　principle　of　progression。　The　next　is　also　eschewed　by　the　majority；　although　many　of　our　best　artists　use　no　other；　on　account　of　the　very　fine　tone　it　gives　to　pictures。

Bromide　of　Iodine。This　is　a　compound　of　bromine　and　chloride　of　iodine。　　In　mixing　it；　much　depends　upon　the　strength　of　the　ingredients；　an　equal　portion　of　each　being　generally　used。　Perhaps　the　best　method　of　preparing　it；　is　to　make　a　solution　in　alcohol　of　half　an　ounce　of　chloride　of　iodine；　and　add　the　bromine　drop　by　drop；　until　the　mixture　becomes　of　a　dark　red　color；　then　dilute　with　distilled　water；　till　it　assumes　a　bright　yellow。　Put　about　half　an　ounce　of　this　compound　into　the　pot；　and　coat　over　it　to　a　violet　color；　change　the　solution　when　it　becomes　too　weak　to　produce　the　desired　effect。

Another。Mix　half　an　ounce　of　bromine　with　one　ounce　of　chloride　of　iodine；　add　two　quarts　pure　distilled　water；　shake　it　well　and　let　it　stand　for　twelve　hours　then　add　twenty…five　drops　of　muriatic　acid；　and　let　it　stand　another　twelve　hours；　occasionally　shaking　it　up　well。　Dilute　six　parts　of　this　solution　in　sixteen　of　water。　　Coat　over　dry　iodine　to　a　deep　yellow；　then　over　the　sensitive　to　a　deep　rose　color　approaching　purplethen　back；　over　dry　iodine　from　four　to　eight　seconds。

Roach's　Tripple　Compound。This　is　one　of　the　very　best　sensitive　solutions；　and　is　very　popular　among　Daguerreotypists。　To　use　this；　take　one　part　in　weight；　say　one　drachm；　of　the　compound　and　dilute　it　with　twelve　of　water；　coat　over　dry　iodine　to　yellow；　then　over　the　compound　to　a　rosy　red。　The　effect　in　the　camera　is　quick；　and　produces　a　picture　of　a　fine　white　tone。

Gurney's　Sensitive。This　is　another　preparation　of　bromine；　and　gives　a　fine　tone。　　To　two　parts　of　water　add　one　of　the　sensitive；　and　put　just　sufficient　in　the　box　to　cover　the　bottom；　or　enable　you　to　coat　in　from　eight　to　ten　seconds。　Coat　over　dry　iodine　to　a　dark　yellow；　and　over　the　quick　till　you　see　a　good　change；　then　back　over　the　dry　iodine　from　two　to　three　seconds。

Bromide　of　Lime；　or　Dry　Sensitive