the history and practice of the art of photography-第23章

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　process；　thus　generally　sketched　out；　by　the　term　Amphitype；a　name　suggested　by　Mr。　Talbot；　to　whom　I　communicated　this　singular　result；　and　to　this　process　or　class　of　processes　（which　I　cannot　doubt　when　pursued　will　lead　to　some　very　beautiful　results；）　I　propose　to　restrict　the　name　in　question；　though　it　applies　even　more　appropriately　to　the　following　exceedingly　curious　and　remarkable　one；　in　which　silver　is　concerned：

At　the　last　meeting　I　announced　a　mode　of　producing；　by　means　of　a　solution　of　silver；　in　conjunction　with　ferro…tartaric　acid；　a　dormant　picture　brought　into　a　forcible　negative　impression　by　the　breath　or　moist　air。　　（See　Cyanotype。）　The　solution　then　described；　and　which　had　at　that　time　been　prepared　some　weeks；　I　may　here　incidentally　remark；　has　retained　its　limpidity　and　photogenic　properties；　quite　unimpaired　during　the　whole　year　since　elapsed；　and　is　now　as　sensitive　as　ever；　a　property　of　no　small　value。　　Now；　when　a　picture　（for　example　an　impression　from　an　engraving）　is　taken　on　paper　washed　with　this　solution；　it　shows　no　sign　of　a　picture　on　its　back；　whether　that　on　its　face　is　developed　or　not；　but　if；　while　the　actinic　influence　is　still　fresh　upon　the　face；　（i。e。；　as　soon　as　it　is　removed　from　the　light）；　the　back　be　exposed　for　a　very　few　seconds　to　the　sunshine；　and　then　removed　to　a　gloomy　place；　a　positive　picture；　the　exact　complement　of　the　negative　one　on　the　other　side；　though　wanting　of　course　in　sharpness　if　the　paper　be　thick；　slowly　and　gradually　makes　its　appearance　there；　and　in　half　an　hour　or　an　hour　acquires　a　considerable　intensity。　I　ought　to　mention　that　the　〃ferro…tartaric　acid〃　in　question　is　prepared　by　precipitating　the　ferro…tartrate　of　ammonia　（ammonia…tartrate　of　iron）　by　acetate　of　lead；　and　decomposing　the　precipitate　by　dilute　sulphuric　acid。　When　lead　is　used　in　the　preparation　of　Amphitype　paper；　the　parts　upon　which　the　light　has　acted　are　found　to　be　in　a　very　high　degree　rendered　water　proof。Sir　J。　Herschel。

This　process　is　a　new　invention　of　our　countryman；　J。　A。　Whipple；　Esq。；　of　Boston；　and　has　been　patented　by　M。　A。　Root；　Esq。；　of　Philadelphia。　It　will　be　seen；　however；　from　the　previous　pages　of　my　work　that　Mr。　Root　is　mistaken　in　regard　to　his　being　the　first　improvement　patented　in　this　country；　althongh　it　is　unquestionably　the　first　by　an　American。　Of　this　improvement　Mr。　Root　says：

VI。　〃CRAYON　DAGUERREOTYPE。〃

〃The　improvement　to　which　you　refer　is　denominated　〃The　Crayon　Daguerreotype。〃　　This　invention　made　by　Mr。　J。　A。　Whipple；　is　the　only　improvement　in　Daguerreotyping；　I　believe；　for　which　Letters　Patent　for　the　United　States　were　ever　issued。　The　pictures　produced　by　this　processwhich　is　of　the　simplest　description　imaginablehave　the　appearance　and　effect　of　very　fine　〃Crayon　Drawings；〃　from　which　the　improvement　takes　its　name。　Some　of　our　most　distinguished　artists　have　given　it　their　unqualified　admiration。　　Among　them；　our　Mezzotinto　Engravers；　especially　John　Sartain；　Esq。；　who；　from　his　rich　embellishments　to　most　of　the　leading　Magazines　and　Annuals　of　the　country；　as　well　as　from　the　celebrity　of　the　superb　Magazine　which　bears　his　name；　is　so　well　known　and　so　well　qualified　to　judge　of　its　merits。　　As　an　auxiliary　to　the　artist；　in　furnishing　heads　to　the　Magazines；　or　other　works；　it　is　invaluable；　the　great　object　which　it　accomplishes　being　to　give　a　finer　effect　and　more　distinct　expression　to　all　the　features　the　whole　power　of　the　instrument　being　directed　to；　and　confined　to　the　head。〃

〃The　late　hour　at　which　this　subject　has　been　brought　to　our　notice　prevents　so　full　a　description　as　we　would　otherwise　have　been　glad　to　furnish。　　The　New　England　States　have　been　disposed　of；　negotiations　for　any　of　the　others　can　be　made　through　M。　A。　Root；　140　Chestnut　street；　Philadelphia。〃

〃A　series　of　beautiful　portraits　are　about　being　prepared　by　the　〃Crayton　Process〃　for　the　express　purpose　of　being　placed　on　the　exhibition　at　the　〃Art　Union；〃　when　amateurs；　artists；　and　the　public　generally　will　have　an　opportunity　of　witnessing　its　effect。　We　are　especially　gratified　with　this　striking　improvement；　from　the　advantages　which　it　promises　to　the　Daguerrean　art。〃

〃It　is　admirably　designed　to　excite　a　new　interest　on　the　subject　through　the　community；　and　in　this　wayand　from　its　tendency　to　render　the　art　more　generally　useful；　and　to　elevate　and　distinguish　it　to　make　it　to　all　a　matter　of　more　general　importance。〃　　〃Yours　respectfully；　　〃M。　A。　ROOT。〃

In　our　second　edition；　we　hopewith　Mr。　Root's　permission　to　lay　the　whole　process　before　the　public；　although　our　artists　must　bear　in　mind　that　Mr。　Root's　patent　secures　to　him　the　exclusive　right　of　its　application。



CHAP。　XI。

ON　THE　PROBABILITY　OF　PRODUCING　COLORED　PICTURES　BY　THE　SOLAR　RADIATIONS　PHOTOGRAPHIC　DEVIATIONSLUNAR　PICTURESDRUMMOND　LIGHT。


Having　before　noticed　the　fact　that　some　advances　had　been　made　towards　taking　Daguerreotypes　in　color；　by　means　of　solar　rays；　and　expressed　the　hope　that　the　day　was　not　far　distant　when　this　might　be　accomplished；　I　here　subjoin　Mr。　Hunt's　remarks　on　this　subject。

Mr。　Biot；　in　1840；　speaking　of　Mr。　Fox　Talbot's　beautiful　calotype　pictures；　considers　as　an　illusion　〃the　hope　to　reconcile；　not　only　the　intensity　but　the　tints　of　the　chemical　impressions　produced　by　radiations；　with　the　colors　of　the　object　from　which　these　radiations　emanated。〃　It　is　true　that　three　years　have　passed　away；　and　we　have　not　yet　produced　colored　images；　yet　I　am　not　inclined　to　consider　the　hope　as　entirely　illusive。

It　must　be　remembered　that　the　color　of　bodies　depends　entirely　upon　the　arrangement　of　their　molecules。　We　have　numerous　very　beautiful　experiments　in　proof　of　this。　The　bi…niodide　of　mercury　is　a　fine　scarlet　when　precipitated。　If　this　precipitate　is　heated　between　plates　of　glass；　it　is　converted　into　crystals　of　a　fine　sulphur　yellow；　which　remain　of　that　color　if　undisturbed；　but　which　becomes　very　speedily　scarlet　if　touched　with　any　pointed　instrument。　This　very　curious　optical　phenomena　has　been　investigated　by　Mr。　Talbot　and　by　Mr。　Warrington。　　Perfectly　dry　sulphate　of　copper　is　white；　the　slightest　moisture　turns　it　blue。　Muriate　of　cobalt　is　of　a　pale　pink　color；　a　very　slight　heat；　by　removing　a　little　moisture；　changes　it　to　a　green。　These　are　a　few　instances　selected　from　many　which　might　be　given。

If　we　receive　a　prismatic　spectrum　on　some　papers；　we　have　evidence　that　the　molecular　or　chemical　disturbance　bears　some　relation　to　the　color　of　each　ray；　or；　in　other　words；　that　colored　light　so　modifies　the　action　of　ENERGIA　that　the　impression　it　makes　is　in　proportion　to　the　color　of　the　light　it　accompanies；　and　hence　there　results　a　molecular　arrangement　capable　of　reflecting　colors　differently。　Some　instances　have　been　given　in　which　the　rays　impressed　correspond　with　the　colors　of　the　luminous　rays　in　a　very　remarkable　manner。*　One　of　the　most　decided　cases　is　that　of　the　paper　prepared　with　the　fluoride　of　soda　and　nitrate　of　silver。　Sir　John　Herschel　was；　however；　the　first　to　obtain　any　good　specimens　of　photographically　impressed　prismatic　colorations。

*　See　Mr。　Hunt's　〃Researches　on　Light。〃

It　was　noticed　by　Daguerre　that　a　red　house　gave　a　reddish　image　on　his　iodized　silver　plate　in　the　camera　obscura；　and　Mr。　Talbot　observed；　very　early　in　his　researches；　that　the　red　of　a　colored　print　was　copied　of　a　red　color；　on　paper　spread　with　the　chloride　of　silver。**

**　In　1842；　I　had　shown　me　a　picture　of　a　house　in　the　Bowery；　which　had　been　repaired　a　few　days　previous；　and　in　the　wall　a　red　brick　left。　　This　brick　was　brought　out　on　the　Daguerreotype　plate　of　precisely　the　same　color　as　the　brick　itself。　The　same　artist　also　exhibited　to　me；　the　full　length　portrait　of　a　gentleman　who　were　a　pair　of　pantaloons　having　a　blue　striped　figure。　This　blue　stripe　was　fully　brought　out；　of　the　same　color；　in　the　picture。AMER。　ED。

〃In　1840　I　communicated　to　Sir　John　Herschel　some　very　curious　results　obtained　by　the　use　of　colored　media；　which　he　did　me　the　honor　of　publishing　in　one　of　his　memoirs　on　the　subject　from　which　I　again　copy　it。〃

〃A　paper　prepared　with　muriate