the history and practice of the art of photography-第14章

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；　the　required　time　is　marked　without　the　possibility　of　error。　In　practice　it　will　be　found　to　be　a　far　more　convenient　instrument　for　the　purpose　than　either　a　clock　or　a　seconds　watch；　and　is　applicable　both　for　the　camera　and　mercury　box。〃

If　the　artist　finds　it　desirable　or　necessary　to　take　the　object　to　be　copied　in　its　right　position；　that　is　reverse　the　image　on　the　spectrum；　he　can　do　so　by　attaching　a　mirror　（which　may　be　had　of　Mr。　Anthony；　or　Mr。　Roach）　to　the　camera　tube；　at　an　angle　of　forty…five　degrees。

If；　after　taking　the　plate　from　the　camera；　it　be　examined；　no　picture　will　yet　be　visible；　but　this　is　brought　about　by　the

FOURTH　PROCESS。Bringing　out　the　Picture；　or　rendering　it　Visible。　We　now　come　to　the　use　of　the　mercury　bath；　Fig。　11。　　To　the　bath　a　thermometer　is　attached；　to　indicate　the　proper　degree　of　beat　required；　which　should　never　be　raised　above　170　deg。　Fahrenheit。　　The　plate　maybe　put　into　one　of　the　frames　（see　Fig。　11；）　over　the　mercury；　face　downwards；　and　examined　from　time　to　time；　by　simply　raising　it　with　the　fingers；　or　a　pair　of　plyers。　　This　operation；　as　well　as　the　others；　should　take　place　in　the　dark　closet。　　＇hipho_26。gif＇　Sometimes；　to　prevent　the　necessity　of　raising　the　plate；　an　additional　cover　or　top　is　made　use　of。　　It　consists　of　a　box　fitted　closely　to　the　inner　rim　of　the　bath；　and　having　an　inclined　top　（a；　Fig。　27。）　The　top　is　cut　through　and　fitted　with　frames　for　each　size　of　plate；　like　those　already　described；　and　in　the　back　is　a　piece　of　glass　（b；）　through　which　to　view　the　progress　of　mercurialization；　and　an　additional　piece　（c；）　on　one　side；　colored　yellow；　to　admit　the　light。　The　outline　only　of　the　top　is　here　given；　in　order　to　show　every　portion　of　it　at　one　view。

The　picture；　being　fully　developed；　is　now　taken　out　and　examined；　it　must　not；　however；　be　exposed　to　too　strong　a　light。　If　any　glaring　defects　be　perceived；　it　is　better　not　to　proceed　with　it；　but　place　it　on　one　side　to　be　re…polished；　if；　on　the　contrary；　it　appears　perfect；　you　may　advance　to　the

FIFTH　OPERATION。Fixing　the　Image　so　that　the　light　can　no　longer　act　upon　it。The　following　articles　are　required　for　this　purpose：

Two　or　three　porcelain　or　glass　dishes；　in　form；　something　like　fig。　24。

A　plate　support；　fig。　25。　　Few；　I　believe；　now　make　use　of　this；　although　it　is　a　very　convenient　article。

Hyposulphite　of　Soda；

A　pair　of　Plyers。

In　Europe；　they　also　use　a　drying　apparatus；　Fig。　27；　but　this；　like　the　plate　support；　　＇hipho_27。gif＇　is　a　matter　of　little　consequence；　and　may　be　dispensed　with。　I　will；　however；　describe　it；　for　the　benefit　of　those　who　may　wish　to　use　it。

A　vessel　made　of　copper　or　brass；　tinned　inside；　and　large　enough　to　take　in　the　largest　plate；　but　not　more　than　half　an　inch　wide；　is　the　most　convenient。　　It　must　be　kept　perfectly　clean。　Hot　distilled　water　is　poured　into　it；　and　the　temperature　kept　up　by　a　spirit　lamp。

Hyposulphite　of　Soda。Having　made　a　solution　of　hyposulphite　of　soda；　and　well　filtered　itthe　strength　is　immaterial；　about　half　an　ounce　of　the　salt　to　a　pint　of　distilled　water　is　sufficientpour　it　into　one　of　the　porcelain　dishes；　put　into　another　plain；　and　into　a　third　distilled　water。　Immerse　the　plate　with　its　face　downwards　into　the　hyposulphite；　and　the　whole　of　the　sensitive　is　removed；　and　the　light　has　no　farther　action　upon　it；　it　is　then　to　be　removed　from　the　hyposulphite　and　plunged　into　the　plain　water；　or　placed　upon　the　support；　fig。　25；　and　the　water　poured　over　it。　It　is　then　washed　in　a　similar　manner　with　the　distilled　water　and　well　examined；　to　see　that　not　the　slightest　particle　of　dust　rests　on　the　suface。　　The　next　step　is　to　dry　it。

This　may　be　readily　accomplished　by　holding　the　plate　with　your　plyers；　and　pouring　distilled　water　over　itif　it　is　hot；　so　much　the　better。　Apply　the　spirit　lamp　to　the　back；　at　the　corner　held　by　the　plyers；　at　the　same　time　facilitating　the　operation　with　the　breath；　pass　the　lamp　gradually　downwards；　finishing　at　the　extreme　corner。　The　last　drop　may　now　be　removed　by　a　little　bibulous　paper。　A　single　drop；　even；　of　distilled　water　allowed　to　dry　on　any　part　of　the　surface；　is　certain　to　leave　a　stain　which　no　after　process　can　remove。

To　illustrate　the　necessity　for　having　perfectly　clean　water；　and　free　from　all　foreign　matteronly　to　be　avoided　by　using　that　which　is　distilled　in　these　processes；　I　will　relate　a　little　anecdote。

An　operator　in　this　city　（New　York）　frequently　made　complaint　to　me；　that　his　plates　were　occasionally　very　bad；　coming　out　all　over　in　little　black　and　white　spots　and　spoiling　many　very　good　pictures；　regretting　at　the　same　time　that　perfect　plates　were　not　made；　for　he　had　lost　many　customers　in　consequence　of　these　defects。　These　complaints　being　somewhat　periodical；　I　suggested　that　the　fault　might　be　in　the　hyposulphite；　or　chloride　of　gold　solutions；　or　particles　of　dust　floating　about　in　the　room；　and　not　in　the　plate。

A　few　days　after　he　stated；　that　his　plates　having　served　him　again　in　the　same　way；　he　procured　a　fresh　supply　of　hyposulphite　of　soda　and　chloride　of　gold；　but　after　applying　them　the　result　was　no　better。　He　then；　by　my　advice；　thoroughly　cleaned　his　wash　dishes；　bottles　and　water　pail；　made　fresh　solutions　and　had　no　further　trouble；　becoming　satisfied　that　the　plates　suffered　an　undue　share　of　censure。

SIXTH　PROCESS。Gilding　the　Picture。This　is　an　improvement　the　honor　of　which　is　due　to　M。　Figeau；　and　may　take　place　either　before　the　drying　process；　or　at　any　subsequent　period；　but　it　improves　the　picture　so　materially　that　it　should　never　be　neglected。　The　articles　necessary　for　gilding　are

A　Pair　of　Plyars；　or　a　Gilding　Stand　（see　fig。　19）　and　Chloride　of　Gold；　or　Hyposulphite　of　Gold。

The　latter　is　imported　by　Mr。　E。　Anthony；　205　Broadway；　New　York；　and　is　decidedly　the　best　article　for　the　purpose。　One　bottle　simply　dissolved　in　a　quart　of　water　will　make　a　very　strong　solution；　and　gives　a　richness　to　the　picture　impossible　to　be　obtained　from　the　chloride　of　gold。　The　process　is　precisely　similar　to　that　described　below　for　chloride　of　gold；　taking　care　to　cease　the　moment　the　bubbles　are　well　defined　over　the　surface　of　the　plate。　Many　Daguerreotypists；　after　a　superficial　trial；　discard　the　hyposulphite　of　gold　as　inferior；　but　I　have　no　hesitation　in　asserting　that　the　fault　lies　with　themselves；　for　in　every　case　within　my　knowledge；　where　its　use　has　been　persisted　in　until　the　correct　method　has　been　ascertained　and　the　nature　of　the　gilding　has　become　familiar；　it　is　always　preferred。　In　illustration　of　this　fact　I　will　relate　an　anecdote：

A　gentleman　to　whom　it　had　been　recommended；　purchased　a　bottle；　and　after　making　one　or　two　trials　of　it；　wrote　to　his　correspondent〃Send　me　two　bottles　of　chloride　of　gold；　for　I　want　no　more　of　the　hyposulphite；　it　is　good　for　nothing。〃　A　few　weeks　after　he　sent　for　three　bottles　of　the　condemned　article；　confessing　that　be　had　found　fault　unnecessarily；　for；　that　since　he　had　become　familiar　to　its　use；　he　must　acknowledge　its　superiority；　and　would　use　no　other　gilding。

The　Solution　of　Chloride　of　Gold　is　prepared　by　dissolving　in　a　pint　of　distilled　water；　fifteen　grains　of　chrystalized　chloride　of　gold。　This　solution　will　be　of　a　yellow　tint。　　In　another　pint　of　distilled　water　dissolve　fifty…five　grains　of　hyposulphite　of　soda；　pour　gradually；　in　very　small　quantities；　the　gold　into　the　hyposulphite　of　soda；　stirring　the　solution　at　intervals；　when　finished　the　mixture　should　be　nearly　colorless。

Place　the　plate　on　its　stand；　or　hold　it　in　the　plyers；　in　a　perfectly　horrizontal　positionsilver　surface　upwardhaving　previously　slightly　turned　up　the　edges；　so　that　it　may　hold　the　solution。　Wet　the　surface　with　alcohol；　letting　any　superfluous　quantity　drain　off。　The　alcohol　is　of　no　farther　use　than　to　facilitate　the　flowing　of　the　gold　mixture　over　the　surface。　　Now　pour　on；　carefully；　as　much　of　the　preparation　of　gold　as　will　remain　on　the　plate。　The　under　part　of　the　plate　is　then　to　be　heated　as　uniformly　as　possible　with　the　spirit　lamp；　small　bubbles　will　arrise；　and　the　appearance　of　the　portrait　or　view　v