the history and practice of the art of photography-第10节

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a　of　the　still　with　the　worm　tub；　or　refrigerator　B；　at　e；　which　is　kept　filled　with　cold　water　by　means　of　the　funnel　c；　and　drawn　off　as　fast　as　it　becomes　warm　by　the　cock　f。　The　distilled　water　is　condensed　in　the　wormand　passes　off　at　the　cock　b；　under　which　a　bottle；　or　other　vessel；　should　be　placed　to　receive　it。　The　different　joints　are　rendered　tight　by　lute；　or　in　its　absence；　some　stiff　paste　spread　upon　a　piece　of　linen　and　wrapped　around　them　will　answer　very　well；　an　addition　of　sealing　wax　over　all　will　make　them　doubly　secure。　　＇hipho_16。gif＇

HYGROMETER。This　is　an　instrument　never　to　be　found；　I　believe；　in　the　rooms　of　our　operators；　although　it　would　be　of　much　use　to　them；　for　ascertaining　the　quantity　of　moisture　floating　about　the　room；　and　as　it　is　necessary　to　have　the　atmosphere　as　dry　as　possible　to　prevent　an　undue　absorption　of　this　watery　vapor　by　the　iodine　&c。；　and　to　procure　good　pictures；its　detection　becomes　a　matter　of　importance。　Mason's　hygrometer；　manufactured　by　Mr。　Roach　and　sold　by　Mr。　Anthony；　205　Broadway；　New　York　is　the　best　in　use。

It　consists　of　two　thermometre　tubes　placed；　side　by　side；　on　a　metalic　scale；　which　is　graduated　equally　to　both　tubes。　The　bulb　of　one　of　these　tubes　communicates；　by　means　of　a　net…work　of　cotton；　with　a　glass　reservoir　of　water　attached　to　the　back　of　the　scale。　　Fig。　17　and　18　represent　a　front　and　back　view　of　this　instrument。

Fig。　　17　is　the　front　view；　showing　the　tubes　with　their　respective　scales；　the　bulb　b　being　covered　with　the　network　of　cotton　communicating　with　the　reservoir　c　fig。　18；　at　d。　　＇hipho_17。gif＇　　＇hipho_18。gif＇　The　evaporation　of　the　water　from　this　bulb　decreases　the　temperature　of　the　mercury　in　the　tube　b　in　proportion　to　the　dryness　of　the　atmosphere；　and　the　number　of　degrees　the　tube　b　indicates　below　that　of　the　other；　shows　the　real　state　of　the　atmosphere　in　the　room；　for　instance；　if　b　stands　at　forty　and　a　at　sixty…one　the　room　is　in　a　state　of　extreme　dryness；　the　difference　of　twenty…one　degrees　between　the　thermometerslet　a　stand　at　any　one　pointgives　this　result。　If　they　do　not　differ；　or　there　is　only　four　or　five　degrees　variation；　the　atmosphere　of　the　room　is　very　moist　and　means　should　be　taken　to　expel　the　superfluous　quantity。

HEAD　RESTS。The　button　head　rest　with　chair　back　clip；　A　fig。　19is　much　the　best　for　travelling　artists；　as　it　can　be　taken　apart；　into　several　pieces　and　closely　packed；　is　easily　and　firmly　fixed　to　the　back　of　a　chair　by　the　clamp　and　screw　a　and　b；　and　is　readily　adjusted　to　the　head；　as　the　buttons　c；　c　and　arms　d；　d　are　movable。

Sometimes　the　button　rest　is　fixed　to　a　pole；　which　is　screwed　to　the　chair；　but　this　method　is　not　so　secure　and　solid　as　the　clip　and　occupies　more　room　in　packing。　　Both　the　pole　and　clip；　are　furnished　in　some　cases　with　brass　band　rests　instead　of　the　button；　but　the　only　recommendation　these　can　possibly　possess　in　the　eyes　of　any　artist；　is　their　cheapness。　　＇hipho_19。gif＇

For　a　Daguerreotypist　permanently　located　the　independent　iron　head…rest；　B　fig。　19；　is　the　most　preferable；　principally　on　account　of　its　solidity。　It　is　entirely　of　iron；　is　supported　by　a　tripod　a）　of　the　same　metal　and　can　be　elevated　by　means　of　a　rod　（b）　passing　through　the　body　of　the　tripod；　to　a　height　sufficient　for　a　person；　standing；　to　rest　against。

GALVANIC　BATTERY。This　article　is　used　for　the　purpose　of　giving　to　imperfectly　coated　plates　a　thicker　covering　of　silver。　The　form　of　battery　now　most　universally　employed　for　electrotype；　and　other　galvanic　purposes；　is　Smee'sFig。　20。　　It　consists　　＇hipho_20。gif＇　of　a　piece　of　platinized　silver；　A；　on　the　top　of　which　is　fixed　a　beam　of　wood；　B；　to　prevent　contact　with　the　silver。　A　binding　screw　C　is　soldered　on　to　the　silver　plate　to　connect　it　with　any　desired　object；　by　means　of　the　copper　wire；　e。　A　plate　of　amalgamated　zinc；　D；　varying　with　the　fancy　of　the　operator　from　one　half　to　the　entire　width　of　the　silver　is　placed　on　each　side　of　the　wood。　　This　is　set　into　a　glass　vessel；　P；the　extreme　ends　of　the　wood　resting　upon　its　edgeon　which　the　acid　with　which　it　is　charged　has　no　effect。　　The　jar　is　charged　with　sulphurid　acid；　（common　oil　of　vitriol）　diluted　in　eight　parts　its　bulk　of　water。　The　zinc　plates　of　the　battery　have　been　amalgamated　with　quicksilver；　and　when　the　battery　is　set　into　the　jar　of　acid　there　should　be　no　action　percieved　upon　them　when　the　poles　F；　G；　are　not　in　contact。　Should　any　action　be　percieved；　it　indicates　imperfect　amalgamation；　this　can　be　easily　remedied　by　pouring　a　little　mercury　upon　them　immediately　after　removing　them　from　the　acid；　taking　care　to　get　none　upon　the　centre　plate　A。

Directions　for　use。A　sheet　of　silver　must　be　attached　to　the　wire　connected　with　the　centre　plate　A　of　the　battery；　and　placed　in　the　silver　solutionprepared　as　directed　below。　The　plate　to　be　silvered　is　first　cleaned　with　diluted　sulphuric　acid；　and　then　attached　to　the　wire；　G；　proceeding　from　the　zinc　plates　D；　D；　and　placed　in　the　silver　solution；　opposite　the　silver　plate　attached　to　the　pole　F；　and　about　half　an　inch　from　it。　A　slight　effervescence　will　now　be　percieved　from　the　battery；　and　the　silver　will　be　deposited　upon　the　Daguerreotype　plate；　while　at　the　same　time　a　portion　of　the　silver　plate　is　dissolved。

To　prepare　the　solution　of　silver。Dissolve　one　ounce　of　chloride　of　silver　in　a　solution　of　two　ounces　of　cyanide　of　potassium；　previously　dissolved　in　one　quart　of　water。　The　oxide　of　silver　may　be　used　instead　of　the　chloride。　This　solution　is　put　into　a　tumbler；　or　other　vessel。　　＇hipho_21。gif＇　　＇hipho_22。gif＇

This　battery　with　the　necessary　articles　for　using　it　may　be　obtained　of　E。　Anthony；　205　Broadway；　New　York　city。

The　other　articles　required　by　every　operator　may　be　simply　enumerated；　viz：

Stickng；　or　sealing　paper。

A　pair　of　pliers；　or　forceps。

Porcelain　pans　or　dishes；　for　applying　the　hyposulphite　of　soda　and　washing　after　the　imagine　is　fixed；　something　in　form　like　fig。　23。

A　support　for　holding　the　plate　while　being　washed；　like　fig。　24　　＇hipho_25。gif＇

BUFF　STICKS。Fig。　25。These　are　usually　from　one　to　three　feet　in　length；　and　about　three　inches　widesome　think　two　and　a　half　sufficient。　The　underside；　which　is　convex；　is　covered　with　a　strip　of　finely　prepared　buckskin；　or　velvet；　well　padded　with　cotton　or　tow。

All　the　articles　enumerated　in　this　chapter　may　be　obtained；　of　the　very　best　quality　and　at　the　most　reasonable　rates；　of　Mr。　E。　Anthony；　205；　Broadway；　New　York。



CHAP。　VI。

THE　DAGUERREOTYPE　PROCESS。

The　process　of　taking　Daguerreotype　pictures　differs　very　materially　from　all　others　of　the　photographic　art；　inasmuch　as　the　production　of　the　image　is　effected　upon　plates　of　copper　coated　with　silver。　The　silver　employed　should　be　as　pure　as　possible；　the　thickness　of　the　plate　is　of　little　consequence；　provided　there　be　sufficient　silver　to　bear　the　cleaning　and　polishingis　free　from　copper　spots；　is　susceptible　of　a　high　polish；　an　exquisitely　sensitive　coating　and　a　pleasing　tone。　These　qualities　are　possessed　to　an　eminent　degree　by　the　French　plates。

Having　already　enumerated　the　various　processesand　the　apparatus　necessary　for　the　manipulation；　I　will　here　give　a　list　of　the　chemicals　to　be　used；　and　then　proceed　to　explain　them　more　fully。　The　requisite　chemicals　are

　NITRIC　ACID；　　　　　　　　　　　　　ROUGE；　　DRY　IODINE；　　　　　　　　　　　　　　MERCURY；　　DRYING　POWDER；　　　　　　　　　　　HYPOSULPHITE　OF　SODA；　　CYANIDE　OF　POTASSIUM；　　　　CHLORIDE　OF　GOLD；　OR　　ROTTENSTONE；　　　　　　　　　　　　　HYPOSULPHITE　OF　GOLD。　　TRIPOLI；　　　　　　　　　　　　　　　　　CHLORIDE　OF　SILVER。　　CHLORIDE　OF　IODINE；　｝　their　compounds；　or　other　　BROMINE　　　　　　　　　　　　　｝　accelerating　mixtures。

FIRST　OPERATION。Cleaning　and　polishing　the　plate。　For　this　purpose　the　operator　will　require　the

Plate　Blocks；

Plate　Vice

Spirit　Lamp；

Polishing　Buffs；

Nitric　Acid；　diluted　in　fifteen　times　its　bulk　of　water

Galvanic　Battery；　to　galvanize　the　plate；　if　it　is　too　imperfect　to　be　used　without；　previous　cleaning　it；　as　directed　in　the　last　chapter。

Rottenstone；

Tripoli；　which　is　too　often　dispensed　with。

Rouge；　or　lampblackthe　first　being　most　preferable。　The　English　operators　mix　the　two　together。

Prepared　cotton　Wool；　or　Canton　flannel。　　If　the　first　is　used；　it　should　be　excluded　from　the　dust；　as　it　is　not　so　easily　cleansed　as　the　latter。

The　plate　is　secured；　with　its　silver　side　upward；　to　the　block；　by　the　means　described　on　page　58having　previously　turned　the　edges　backward　all　around。　　The　amount　of　cleaning　a　plate　requires；　depends　upon　the　state　it　is　in。　　We　will　suppose　one　in　the　worst　condition；　dirty；　scratched；　and　full　of　mercury　spots；　all　of　which　imperfections　are　more　or　less　to　be　encountered。　The　mercury　spots　are　to　be　removed　by　burning　the　plate。　To　do　this　hold　the　plate　over　the　flame　of　a　spirit　lamp；　more　particularly　under　the　mercury　spots；　until　they；　assume　a　dull　appearance；　when　the　lamp　is　to　be　removed；　and　the　plate　allowed　to　cool；　after　which　it　is　attached　to　the　block。

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　b