american hand book of the daguerreotype-第18部分

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　shades。　Of　these　three　modes　of　bringing　out　the　image；　the　second　is　superior　to　the　others。


MANAGEMENT　OF　CHEMICALS。

It　is　necessary；　first　of　all；　to　know　that　you　have　a　chemical　which　is　capable　of　producing　good　results　when　in　skillful　hands。　For　this　reason　it　is　best　to　prepare　your　own　quick；　after　some　formula　which　is　known　to　be　good。　　Those　quick…stuffs　which　contain　chloride　of　iodine　are　noted　for　their　depth　of　tone　while　they　probably　operate　with　less　uniformity　than　those　which　are　destitute　of　it。　For　operating　under　ordinary　circumstances；　especially　with　an　inferior　light；　probably　no　accelerator　is　more　quick　and　sure　than　Wolcott's。　It　also　produces　a　very　fine；　white　pleasing　picture；　though　lacking　that　depth　of　impression　so　much　to　be　desired。　The　dry　quick　operates　with　surety；　and　its　use　is　simple　and　easy；　producing　an　impression　much　like　Wolcott's。　For　those　having　a　good　and　permanent　light；　however；　we　would　recommend　a　chemical　giving　more　body　to　the　impression。

There　is　a　class　of　accelerators　called　sensitives；　claiming　to　work　in　from　three　to　ten　seconds；　which；　however；　will　be　found　very　little；　if　any；　more　sensitive　than　this。　　We　frequently　work　it　with　the　ordinary　coating　in　twelve　and　fifteen　seconds。　The　manner　in　which　the　sensitives　are　worked　is　by　coating　very　light。　In　this　way；　a　flat；　shallow　picture　is　obtained　in　a　few　seconds；　and　the　same　can　be　done　with　any　of　the　more　volatile　quicks。

It　is　a　fact　not　generally　known；　that　a　plate　coated　in　a　light　chemical　room　is　more　sensitive　than　when　coated　in　darkness。　By　admitting　a　free；　uniform　light；　and　exposing　the　plate　to　it　a　few　seconds　after　coating；　then　timing　short　in　the　camera；　a　very　light；　clear　impression　is　obtained。　　The　time　in　the　camera　is　reduced　in　proportion　to　the　previous　action　of　light。　　The　shades；　of　course；　are　destroyed；　and　the　tone　injured；　still；　for　taking　children；　we　have　succeeded　better　by　this　method　than　by　the　use　of　〃sensitives。〃　The　discovery　of　this　principle　was　accidental；　while　operating　where　the　direct　ray　s　of　the　sun；　entering　the　window　just　before　sunset；　fell　on　the　curtain　of　our　dark　room；　rendering　it　very　light　within。

The　selection　of　iodine　is　not　unimportant。　　Reject；　at　once；　that　which　has　anything　like　a　dull；　black；　greasy　appearance；　and　select　that　which　is　in　beautiful　large　crystalline　scales；　of　a　purple　color；　and　brilliant　steel　lustre。

Solarization；　and　general　blueness　of　all　the　light　parts　of　the　picture；　were　formerly　great　obstacles　to　success；　though　now　scarcely　thought　of　by　first…class　artists。　　Beginners　in　the　art；　however；　are　still　apt　to　meet　with　this　difficulty。　It　is　occasioned　by　dampness　in　the　iodine　box；　which　causes　the　plate　to　become　coated　with　a　hydro…iodide　of　silver；　instead　of　the　iodide。　　The　remedy　is　in　drying　your　iodine。　If　in　summer；　you　can　open　your　box　and　set　it　in　sunshine　a　few　minutes；　or　if　in　winter；　set　it　under　a　stove　a　short　time。　The　true　method；　however；　is　to　dry　it　by　means　of　the　chloride　of　calcium。　　It　has　such　a　remarkable　affinity　for　water；　that　a　small　fragment　placed　in　the　open　air；　even　in　the　dryest　weather；　soon　becomes　dissolved。

Take　one　or　two　ounces　of　this　chemical；　heat　it　in　the　drying　bath；　or　in　a　hot　stove；　to　perfect　dryness；　place　it　in　a　small　glass　toy　dish；　or　large　watch　crystal；　and　set　it　in　the　centre　of　your　iodine　box。　Take　this　out　and　heat　to　dryness　every　morning。　　Adopt　this　process；　and　with　your　mercury　at　a　high　temperature；　you　will　never　be　troubled　with　blue　pictures。

Young　operators　are　apt　to　impute　all　want　of　success　in　operating　to　their　chemicals；　even　though　the　cause　is　quite　as　likely　to　be　elsewhere。　Failure　is　quite　likely　to　occur　from　dampness　in　the　buffs；　or　in　the　polish；　it　is　therefore　necessary　to　be　constantly　on　the　guard　in　this　quarter。　With　a　view　to　this；　always　scrape　your　buffs　with　a　dull　knife；　or　with　one　blade　of　your　shears；　the　first　thing　in　the　morning；　and　after　brushing　them　thoroughly；　dry　them；　either　in　the　sun；　by　a　stove；　or　in　the　buff…dryer。　It　is　equally　important　that　the　polish　and　the　brush　should　be　kept　dry。

Want　of　success　may　arise　from　vapors　of　iodine　or　bromine　in　the　camera　box；　mercury　bath；　or　even　in　the　buffs。　　It　is　incredible　how　small　a　quantity　of　these　vapors　will　affect　the　effect　of　light　when　coming　in　contact　with　the　plate；　after　or　during　the　exposure　in　the　camera。　It　is　therefore　necessary　to　be　cautious　not　to　mix　chemicals；　nor　open　your　boxes　or　bottles　in　your　room；　but　take　them　out　to　do　it。　Never　hurry　the　operation　through　from　lack　of　confidence　in　the　result。　The　fact　of　anything　being　out　of　order；　forms　no　excuse　for　slighting　the　process。　　If　unsuccessful；　do　not　pursue　the　same　course　every　trial；　but　vary　with　a　view　to　detect　the　cause　of　the　difficulty。

In　case　of　a　long　series　of　failures；　institute　a　regular　course　of　investigation；　after　this　manner；　commencing　where　the　trouble　is　most　likely　to　occur：

1。　　Are　the　plates　well　cleaned？

2。　　Is　the　iodine　dry？　　If　the　impressions　come　out　blue；　you　may　rest　assured　it　is　not。　　Take　out　the　iodine；　wipe　and　dry　the　box；　and　dry　the　calcium。

3。　　Is　the　quick　battery　of　the　right　strength？　　If　dry；　it　must　change　the　plate　in　from　six　to　fifteen　seconds。　If　any　of　the　chloride　of　iodine　class；　it　may　vary　from　five　seconds　to　a　minute。　　Begin　by　coating　light；　and　increase　on　each　trial；　observing　the　effect。　If　the　light　side　of　the　picture　seems　loth　to　come　out；　and　shows　no　contrast　with　the　dark　side；　it　is　to　be　inferred　that　your　battery　is　too　strong；　and　must　be　reduced　with　water　or　set　out　in　the　open　air　for　a　few　minutes；　with　the　lid　off。　If　working　an　old　battery；　never　renew　very　strong；　or　it　will　work　dark　and　heavy。　　A　battery；　to　work　well；　should　be　gradually　losing　strength；　but　never　gaining。　An　old　battery；　however；　may　be　quickened　up　and　made　to　work　well　for　some　time；　by　adding　five　of　six　drops　of　sulphuric　acid；　repeating　the　quantity　as　often　as　necessary；　providing　always　that　acid　be　not　used　in　manufacturing　the　quick。

4。　　Have　the　plates　lost　their　sensitiveness　by　being　many　times　exposed　to　mercury？　　Clean　and　burn　them；　but　if　French　plates；　burn　light；　or　you　spoil　them。

5。　　Are　the　buff　s　dry　and　clean？　　Examine　the　plate　critically　after　buffing　to　detect　any　appearance　of　scum　or　film　on　the　surface。　　If　so；　the　longer　you　buff　the　more　it　shows。　Scrape　and　dry　the　buffs　thoroughly。

6。　　Is　the　mercury　free　from　scum　and　dirt？　　If　not；　filter。　Is　it　also　far　enough　from　the　coating　boxes？　　Should　be　at　least　three　feet；　and　kept　covered。

7。　　Is　the　mercury　sufficiently　heated？　　This　is　important。　Long　exposure；　however；　will　answer　the　same　purpose。

8。　　Are　your　lenses　clean；　and　in　proper　place？

9。　　Are　the　tablets　in　focus　with　the　ground…glass？　If　you　can　attribute　the　failure　to　none　of　these；　mix　a　new　box　of　some　other　kind　of　quick；　say　the　dry；　for　instance。　　If　you　fail　in　the　same　manner　here；　take　time；　wash　your　buffs；　overhaul　all　the　chemicals；　and　start　anew。　Do　not　be　discouraged。

There　is　no　day　so　dark　but　that　the　sun　will　shine　again。　We　will　close　with　this　brief　summary　of　advice：

Clean　your　plates。　　Keep　everything　dry。　　Keep　the　mercury　hot。　Follow　these　instructions　carefully；　and　you　must　succeed。


HINTS　AND　CAUTIONS。

First　of　all；　cleanliness　should　be　observed。　　When　there　is　dust　or　dirt　about　your　room；　particularly　about　the　work…bench；　failures　will　be　frequent；　for　the　smallest　particles　of　rotten…stone；　when　allowed　to　come　in　contact　with　the　buffs；　will　produce　scratches　on　the　surface　of　the　plate；　which　very　much　injures　the　operation；　and　often　causes　failures。

Dust　flying　about　the　room　is　injurious；　if　allowed　to　fall　on　the　plate；　either　before　or　after　it　has　been　coated；　as　it　causes　black　spots　which　cannot　be　removed。

The　polished　plate　should　not　be　allowed　to　come　in　contact　with　a　strong　current　of　air；　for　it　tends　to　oxidize　the　surface。　Breathing　on　the　surface　should　also　be　avoided；　for　the　same　reason。

The　plate　should；　in　all　cases；　be　buffed　immediately　before　using；　and　not　allowed　to　stand　any　length　of　time。　It　should　be　held　with　the　polished　face　downward。

It　is　always　best　that　the　plate　should　be　of　the　same　temperature　of　the　atmosphere　in　the　room。

Keep　the　camera　and　mercury…bath　perfectly　free　from　the　vapors　of　iodine　and　bromine；　for　the　presence　of　the　slightest　degree　of　either　of　the　above　will　injure　the　impression　in　no　small　degree。　As　a　preventive；　let　the　camera　be　exposed　to　the　sun　or　fire　for　a　few　minutes　in　the　morning。

Filter　your　mercury　often；　to　keep　the　surface　free　from　film　and　dust。

The　hyposulphite　solution　should　be　filtered　through　sponge　every　time　it　is　used。

The　direct　rays　of　light　must　not　enter　the　camera　in　conjunction　with　those　reflected　from　the　object；　or　the　picture　will　be　veiled；　and　the　color　of　the　plate　changed　to　a　thick　green。

If　the　plate　be　iodized　only　to　a　light…yellow；　the　result　might　be　of　a　bluish　or　grey　tinge：　　and　this　is　generally　the　case；　when　the　quick　is　new　and　strong；　and　there　is　an　excess　of　it　on　the　plate；　and　yet　not　enough　to　form　the　bromide　iodide　of　silver；　in　which　case　it　would　wholly　spoil　the　impression。

Your　iodine　will　be　found　to　operate　more　successfully；　when　the　time　required　for　coating　the　plate　does　not　fall　short　of　fifteen　seconds；　or　exceed　one　minute。

Too　quick　coating　can　be　avoided　by　using　less　iodine　in　your　box。　In　the　summer　months；　when　the　weather　is　80　deg。　　and　over；　one　quarter　of　an　ounce；　or　even　less；　will　work　to　advantage。


ELECTROTYPING。

I　am　indebted　to　Mr。　J。　H。　Fitzgibbons　for　the　following　process；　which　he　employed　in　producing　the　excellent　specimens　he　exhibited　at　the　Crystal　Palace：

〃I　shall　endeavor　to　lay　down　in　as　comprehensive　a　manner　as　possible　the　method　by　which　I　have　been　enabled　to　produce　the　most　satisfactory　results。　I　use　a　Smee's　battery　（another　kind　will　do）。　After　filling　the　cell；　of　common　size；　nearly　full　with　water；　add　about　quarter　of　an　ounce　of　sulphuric　acid。　　Mix　thi