the history and practice of the art of photography-第12部分

快捷操作: 按键盘上方向键 ← 或 → 可快速上下翻页 按键盘上的 Enter 键可回到本书目录页 按键盘上方向键 ↑ 可回到本页顶部! 如果本书没有阅读完，想下次继续接着阅读，可使用上方 "收藏到我的浏览器" 功能 和 "加入书签" 功能！


　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　very　sensibly　improved。　The　process　must　not　be　carried　too　far；　but　as　soon　as　the　bubbles　disappear　the　lamp　should　be　removed；　and　the　plate　immersed　in　distilled　water；　and　dried　as　before　directed。

7th。　COLORING　THE　PICTURE。I　very　much　doubt　the　propriety　of　coloring　the　daguerreotypes；　as　I　am　of　opinion；　that　they　are　little；　if　any；　improved　by　the　operation；　at　least　as　it　is　now　generally　practised。

There　are　several　things　requisite　in　an　artist　to　enable　him　to　color　a　head；　or　even　a　landscape　effectively；　and　correctly；　and　I　must　say　that　very　few　of　these　are　possessed　by　our　operators　as　a　class。　These　requirements　are；　a　talent　for　drawingtastedue　discrimination　of　effectstrict　observance　of　the　characteristic　points　in　the　features　of　the　subjectquick　perception　of　the　beautiful；　and　a　knowledge　of　the　art　of　mixing　colors；　and　blending　tints。

The　method　now　pursued；　I　do　not　hesitate　to　say；　and　have　no　fears　of　being　contradicted　by　those　capable　of　critisizing　is　on　the　whole　ruinous　to　any　daguerreotype；　and　to　a　perfect　one　absolutely　disgusting。　The　day　may　come　when　accurate　coloring　may　be　obtained　in　the　camera。　Until　that　day；　if　we　cannot　lead　taste　into　the　right　channel；　we　will　endeavor　to　give　such　instructions　that　Daguerreotypists　may　proceed　with　this　part　of　his　work　with　a　better　understanding　of　the　principles　involved。　For　this　purpose　I　have　prepared　a　short　chapter　on　the　art　of　coloring；　which　may　be　found　in　the　latter　part　of　this　volume。

To　Preserve　Daguerreotypes　they　must　be　well　sealed　and　secured　in　a　case；　or　frame。　　These；　of　course；　are　selected　according　to　the　taste　of　the　customer；　the　principal　requisite　being　good　glass。　Most　Daguerreotypists　prefer　the　white　French　plate　glassand　many　think；　very　erroneously；　that　none　is　good　unless　it　is　thick　but　the　great　desideratum　is　clearness　and　freedom　from　blisters；　even　glass　a　little　tinged　with　green　or　yellow　is　to　be　preferred　to　the　French　plate　when　cloudy　or　blistered　and　there　is　very　little　of　it　comes　to　this　market　that　is　not　so。　It　is　to　be　hoped　that　some　of　our　glass　factories　will　manage　to　manufacture　an　article　expressly　for　daguerreotypes；　and　I　would　recommend　them　to　do　so；　for　they　would　find　it　quite　an　item　of　profit　annually。

Before　enclosing　the　picture　in　the　case　you　should　be　careful　to　wipe　the　glass　perfectly　clean；　and　blow　from　the　picture　any　particles　of　dust　which　may　have　fallen　upon　it。　Then　take　strips　of　sticking　paper；　about　half　or　three　quarters　of　an　inch　wide；　and　firmly　and　neatly　secure　it　to　the　glass；　having　first　placed　a　〃mat〃　between　them　to　prevent　the　plate　being　scratched　by　the　glass。

TO　MAKE　SEALING　PAPER。Dissolve　one　ounce　of　gum　arabic；　and　a　quarter　of　an　ounce　of　gum　tragicanth　in　a　pint　of　water；　then　add　a　teaspoonful　of　benzoin。　　Spread　this　evenly　on　one　side　of　good　stout　tissue　paper；　let　it　dry；　and　then　cut　it　up　in　stripes；　about　half　or　three　quarters　of　an　inch　wide；　for　use。　If　it　becomes　too　soft　for　summer　use；　add　gum　arabic；　if　too　hard　and　cracking；　add　benzoin　or　gum　tragicanth；　if　it　gets　too　thick；　add　water。

COLORED　DAGUERREOTYPES　ON　COPPER。To　effect　this；　take　a　polished　plate　of　copper　and　expose　it　to　the　vapor　of　iodine；　or　bromine；　or　the　two　substances　combined；　or　either　of　them　in　combination　with　chlorine。　This　gives　a　sensitive　coating　to　the　surface　of　the　plate；　which　may　then　be　submitted　to　the　action　of　light　in　the　camera。　After　remaining　a　sufficient　time　in　the　camera；　the　plate　is　taken　out　and　exposed　to　the　vapor　of　sulphuretted　hydrogen。　This　vapor　produces　various　colors　on　the　plate；　according　to　the　intensity　with　which　the　light　has　acted　on　the　different　parts；　consequently　a　colored　photographic　picture　is　obtained。　No　further　process　is　necessary　as　exposure　to　light　does　not　effect　the　picture。

By　this　process　we　have　an　advantage　over　the　silvered　plate；　both　in　economy；　and　in　the　production　of　the　picture　in　colors。

INSTANTANTANEOUS　PICTURES　BY　MEANS　OF　GALVANISM。It　will　be　seen　by　the　following　valuable　communication　that　galvanism　can　be　successfully　applied　in　producing　pictures　instantly；　a　process　of　great　importance　in　securing　the　likeness　of　a　child；　or　in　taking　views　of　animated　nature。　Colonel　Whitney　informs　me　that　he　once　took　a　view　of　the　steeple　of　the　St。　Louis　Court　House　after　sundown　by　this　means）　and　also　secured　the　image　of　a　man　in　the　act　of　stepping　into　a　store；　and　before　he　had　time　to　place　his　foot；　raised　for　that　purpose；　on　the　door　step。　Mr。　Whitney　is　well　known　as　the　talented　editor　of　the　Sunday　Morning　news。


　New　York；　January　16；　1849。　　Mr。　H。　H。　SNELLING。

Dear　Sir；As　you　are　about　publishing　a　history　of　the　Daguerreotype；　and　request　a　description　of　my　mode　of　taking　pictures　instantaneously　by　the　aid　of　galvanism；　I　comply　with　great　pleasure。

In　the　year　1841；　while　practicing　the　art　in　St。　Louis；　Mo。；　I　was　at　times；　during　the　summer；　much　troubled　with　the　electric　influence　of　the　atmosphere；　especially　on　the　approach　of　a　thunder…storm。　At　such　times　I　found　the　coating　of　my　plates　much　more　sensitive　than　when　the　atmosphere　was　comparatively　free　from　the　electric　fluid；　and　the　effect　was　so　irregular　that　no　calculation　could　counteract　the　difficulty。　This　satisfied　me　that　electricity　was　in　some　measure　an　important　agent　in　the　chemical　process；　and　it　occurred　to　me　that　the　element　might　be　turned　to　advantage。　I　determined；　therefore；　to　enter　on　a　series　of　experiments　to　test　my　theory。　　Finding　it　impossible　to　obtain　an　electric　machine；　and　unwilling　to　abandon　the　examination；　it　occurred　to　me；　that　the　galvanic　influence　might　answer　the　same　purpose。　I　therefore　proceeded　to　make　a　galvanic　battery　in　the　following　simple　manner。　　I　obtained　a　piece　of　zinc　about　two　inches　long；　one　inch　wide；　and　an　eighth　of　an　inch　thick。　On　this　I　soldered　a　narrow　strip　of　copper；　about　six　inches　long；　the　soldered　end　laid　on　one　side　of　the　zinc；　and　extending　its　whole　length。　　The　battery　was　completed　by　placing　the　zinc　in　a　glass　tumbler；　two…thirds　full　of　dilute　sulphuric　acid；　strong　enough　to　produce　a　free　action　of　the　metals。　The　upper　end　of　the　copper　slip　extending　above　the　tumbler　was　sharpened　to　a　point；　and　bent　a　little　over　the　glass。

The　method　of　using；　was　thus：After　preparing　the　plate　in　the　usual　manner　and　placing　it　in　the　camera；　in　such　manner　as　to　expose　the　back　of　the　plate　to　view；　the　battery　was　prepared　by　placing　the　zinc　in　the　acid；　and　as　soon　as　the　galvanic　fluid　began　to　traverse　（as　could　be　known　by　the　effervessence　of　the　acid；　operating　on　the　zinc　and　copper）　the　cap　of　the　camera　was　removed；　and　the　plate　exposed　to　the　sitter；　at　the　same　instant　the　point　of　the　battery　was　brought　quickly　against　the　back　of　the　plate；　and　the　cap　replaced　instantly。　　If　the　plate　is　exposed　more　than　an　instant　after　the　contact　the　picture　will　generally　be　found　solarized。　By　this　process　I　have　taken　pictures　of　persons　in　the　act　of　walking；　and　in　taking　the　pictures　of　infants　and　young　children　I　found　it　very　useful。　　Very　respectfully　yours；　　THOMAS　R。　WHITNEY。



CHAP。　VII

PAPER　DAGUERREOTYPES。ETCHING　DAGUERREOTYPES。


Mr。　Hunt　describes　a　process；　discovered　by　himself　by　which　the　Daguerrean　art　may　be　applied　to　paper。　His　description　is　as　follows：

〃Placing　the　paper　on　some　hard　body；　wash　it　over　on　one　side　by　means　of　a　very　soft　camel's　hair　pencilwith　a　solution　of　sixty　grains　of　bromide　of　potassium；　in　two　fluid　ounces　of　distilled　water；　and　then　dry　it　quickly　by　the　fire。　Being　dry；　it　is　again　washed　over　with　the　same　solution；　and　dried　as　before。　　A　solution　of　nitrate　of　silver　one　hundred　grains　to　an　ounce　of　distilled　wateris　to　be　applied　over　the　same　surface；　and　the　paper　quickly　dried　in　the　dark。　In　this　state　the　papers　may　be　kept　for　use。

〃When　they　are　required；　the　above　solution　of　silver　is　to　be　plentifully　applied；　and　the　paper　placed　wet　in　the　camera；　the　greatest　care　being　taken　that　no　day　light　not　ev