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Encyclopedic Dictionary of Photography

Photo
Photo Ceramics.—a Process Of Producing Burnt-in Photographic Images On Porcelain, Pottery, Glass And Other Similar Materials. There Are Two Principal Methods—the Substitution Process Invented By Du Motay And Marechal, And The Dusting-on Process Of Poitevin. The Best Description Of The Substitution Process Is That Of Mr. N. K. Cherrill, And ...

Picric Acid
Picric Acid (formula, ; Synonym, Carbazotic Acid).—prepared By The Action Of Nitric Acid On Phenol. It Takes The Form Of Yellow Plates Or Prisms, Sparingly Soluble In Cold Water, But More Easily On Heating, Giving It A Bright Yellow Color ; Alcohol Dissolves It Readily. It Has Been Used As ...

Pinhole Photography
Pinhole Photography. —it Is A Well-known Fact That, Although The Lens Is The Most Important Part Of The Graphic Apparatus, Pictures Can Be Made Entirely Without Its Use Very Passable Negatives Can Be Made By Means Of A Small Hole In A Rectangular Light-tight Box, And A Plate Fixed At ...

Platinotype
Platinotype Process.—a Process Of Positive Printing From The Negative, Giving Pic Tures Of Remarkable Softness And Artistic Quality. As Far Back As 1832 Sir J. Herschel Gave An Account Of His Experiments On The Action Of Light Upon Salts Of Platinum. Later On In 1844 Hunt Pointed Out The Fact ...

Platinum
Platinum Toning.--as Is Generally Known The Chief Substance Used In Photography For Toning The Photographic Image To An Agreeable Color Is Gold. The Chemical Similarity Between Gold And Platinum Led To Experiments Being Made With The Latter Metal To Replace The Former. The First Published Formula For A Platinum Toning ...

Porcelain Paper
Porcelain Paper. —a Paper Having A Prepared Surface Resembling Finely-ground Por Celain, And Upon Which Very Effective Silver Prints May Be Made, As The Preparation, Although Without Gloss, Serves To Keep The Image On The Surface. The Following Instructions For Its Manufacture Have Been Published.* Any Sheet Of A Saxe, ...

Portable
Portable Apparatus.—a Term Given To Light, Compact Photograph Apparatus, Suit Able For Tourists Or Out-door Photography. Portraiture.—portrait Photography Is One Of The Most Difficult Branches Of The Art, And Requires Considerable Experience And Artistic Culture. Amateur Photographers, As A Rule, Fail In Their Attempt At This Class Of Work Owing ...

Potassium
Potassium Oxalate.—(formula, ; Molecular Weight, 164; Synonym, Neutral Oxalate Of By Neutralizing Oxalic Acid With Caustic Potash Or Potassium Car Bonate. Obtained In White Crystalline Masses Or In Powder. As It Is Always Used In The Liquid State, The Following Simple Method For Preparing It In That Form Will Be ...

Potassium Chloro Platinite
Potassium Chloro-platinite (formula, —takes The Form Of Reddish Deliquescent Crystals, Very Soluble In Water, But Slightly In Alcohol. It Should Dissolve In Water Without Any Residue And Give A Neutral Solution. Messrs. Pizzighelli And Htibl In Their Work On The Platinotype Process Give The Following Instructions For Its Manufacture : ...

Potassium Cyanide
Potassium Cyanide (formula, Kcn; Molecular Weight, 65; Synonyms, Cyanide, Cyanide Of By Fusing In An Iron Crucible A Mixture Of Eight Parts Of Well-dried Potas Sium Ferro-cyanide With Three Parts Of Potassium Carbonate. When Effervescence Has Ceased And The Iron Which Separates Has Settled Down, The Clear Liquid Is Poured ...

Potassium Dichromate
Potassium Dichromate (formula, K,cr,o, ; Molecular Weight, 293; Synonyms, Bkhro .mate Of Potash, Potassium Anhydrochromatc, Red Chromate Of Potash, Acid Chromate Of Potash.)—the Chrome Iron Ore Is First Heated To Redness And Thrown Into Water; It Can Then Be Easily Ground To A Fine Powder, Which Is Mixed With Potassium ...

Powder Process
Powder Process, Also Known As The " Dusting On " Process.—a Method Of Producing Photographic Images In Any Color Upon Paper, Glass, Metal, Or Other Supports. The Principle Of The Process Is This : An Organic Tacky Substance Is Sensitized With Potassium Dichromate, And Exposed Under A Reversed Positive To ...

Primuline Process A
Primuline Process.--a Recent Process Invented By Messrs. Green, Cross And Bevan. It Is Better Known, However, As The " Diazotye Process." The Following Description Of It Is Partly Taken From A Lecture Given By The Inventors*:- This Process In Reality Consists Of A New Application Of A Group Of Colored ...

Printers
Printers' Indicator.—a Small Brass Instrument That Can Be Attached To Printing Frames. It Contains Two Dials With Figures, And Two Movable Hands ; One Hand Indicates The Num Ber Of Prints Required From The Negative, And The Other The Number Already Printed. Printing.—this Term Is Applied To A Very Large ...

Printing
Printing Frame.—a Frame In Which The Sensitive Surface Of The Paper Is Pressed Into Close Contact With The Face Of The Negative While It Is Being Exposed To The Light. The Ordinary Printing Frame Consists Of A Wooden Box-shaped Frame, Having A Hinged Lid To Allow Of The Examination Of ...

Printing Drawing Paper
Drawing Paper, Printing On.—very Good Effects May Be Produced By Printing With Silver Chloride On A Rough Drawing Paper Such As Whatman's. The Picture Should Not Be Mounted, But Printed Like Engravings With Very Wide Margins. The Roughness Of The Drawing Paper Gives That Artistic Dull Appearance Of The Engraving. ...

Printing Plain Paper
Plain Paper, Printing On.—plain Paper May Be Printed On And Made To Yield Very Artistic Results. For This Purpose We Require A Good Class Of Paper, Such As Saxe Or Rives. This S Sized With Gelatine Or Albumen. A Very Good Formula Is The Following : Albumen I Ounce Water ...

Printing On Silk
Silk, Printing On. —photographic Positives Can Be Made Very Effective Printed Upon Silk, Satin, Or Other Fabrics. There Are Several Methods Of Accomplishing This. A Simple One Is The Following: The Silk Best Suited For The Purpose Is That Known As Chinese Silk, And This Is First Washed In Warm ...

Process
Process Blocks.—printing Blocks Obtained By The Aid Of Photographic Processes. The Following Excellent Instructions For The Production Of Half-tone Or Process Blocks By The Modern Methods Are Given By Mr. Robert Whittet : Initiatory Process In Its Entirety Consists Of Three Distinct Operations : R. Making The Negative. 2. The ...

Pyrocatechin
Pyrocatechin (formula, C,h, (oh), ; Synonyms. Catechol, Oxypjecnic Acid, Brenexatechin, Pyromorintannic Acid).—obtained By The Dry Distillation Of Catechu Extracted From The Inner Bark Wood Of The Acacia Catechu, And Also From Kino, Another Similar Extract. The Leaves Of The Virginia Creeper Contain Pyrocatechin. It Is Also Obtained By Fusing Phenol-sulphonatic ...

Pyrogallic
Pyrogallic Developer.—development With Pyrogallol, Or Pyrogallic Acid, As It Is Erroneously Termed, In A Solution With An Alkali, Is More General Than With Any Other. One Of The Chief Advantages With This Form Of Developer Is The Power Of The Operator Possesses Of Vary Ing It To Suit The Requirements ...

Pyrogallol
Pyrogallol (derived From Gallic Acid And Heat). Formula, Molecular Weight, 126; Synonyms, Trihydroxybenzene, Pyrogallic Acid, Pyrogallin, Trihydroxybenzene Derived From Gallic Acid By Destructive Distillation, Carbon Dioxide Being Given Off As One Of The Products Of Decomposition, Thus: It Is Prepared As Follows: Gallic Acid Dried At Ioo Deg. C. Is ...

Pyroxylin
Pyroxylin (formula H ; Molecular Weight, 252; Synonyms, Pyroxyline, Gun Cotton). This Name Is Applied To A Series Of Compounds Obtained By Acting On Vegetable Fibres With Nitric And Sulphuric Acids. They Are All More Or Less Explosive, And Are All What Are Termed Substitution Compounds, Being Derived From The ...

Radical
Radical Cor1pound.—in Organic Chemistry A Compound -adical Is A Group Of Elements Which, In The Various Changes And Lecompositions Which A Substance Undergoes, Remains Unaffected, Ind Acts As If It Were An Element. Cyanogen, Ethyl, Etc.. Are Corn Iound Radicals. Rapidity.—the Rapidity Of A Lens Is Dependent Upon The Relation ...

Reflectors
Reflectors, Silvering.—see Mirror, Silvering. Refraction.—the Bending Or Deflection Of A Ray Of Light (including Heat And All Other Forms Of Radiant Energy) Which Takes Place Whenever The Ray Passes At Any Other Angle Than A Right Angle From The Surface Of One Medium Into Another Medium Of Different Density. This ...

Refractive Index Or Index
Refractive Index Or Index Of Refraction.—when A Ray Of Light Passes Obliquely From A Rare To A Dense Medium It Is Refracted To A Certain Extent, Varying With The Medium Employed, As The Sine Of The Angle Of Incidence Always Bears An Invariable Ratio To That Of The Angle Of ...

Repeating
Repeating Back.—a Form Of Single Plate-holder So Arranged That Two Separate Nega Tives May Be Made Upon One Plate. There Are Many Forms Of Studio Cameras With Repeating Backs, Enabling The Operator To Take Two Cabinet Or C.-de-v. Pictures Upon One Plate. Repeating Backs Are Also Used For Single Stereoscopic ...

Restoring
Restoring Prints.--prints When Kept Some Time Previous To Toning Will Often Turn Yellow Or Brown, And Become Completely Discolored. This May, However, Be Restored By Placing Immediately Before Toning In A Two Per Cent. Solution Of Strong Ammonia. After Toning They Are Washed In A Bath Of Similar Strength, And, ...

Reversed
Reversed With The Image Reversed In Position As Regards Right And Left. In Photo-mechanical Printing This Is A Necessity, Otherwise The Prints Finally Obtained Would Be Incorrect, The Right Side Being To The Left, And Vice Versa. Reversed Negatives Can Be Made In Several Different Ways. These Can Be Divided ...

Roll Holder Or Roller
Roll Holder Or Roller Slide.—an Arrangement For Holding A Continuous Band Of Paper Or Other Flexible Substance, Coated With A Sensitive Emulsion, In The Camera During Expo Sure. The First Roller Slide Was Introduced By Mr. A. Melhuish, About The Year 1861, And Was Used For Making Paper Negatives. In ...

Sensitized
Sensitized Paper.—this Term Properly Includes Any Kind Of Prepared Paper Sensitive To Light, The Action Being Either Visible Or Latent And Made Visible By Development. It Is More Generally Applied, However, To Albumenized Or Plain Paper Treated With A Chloride And Afterwards Floated On Nitrate Of Silver. See Sensitizing. Sensitized ...

Sensitizing
Sensitizing Bath.—see Silver Bath. Sensitometer.—an Instrument For Comparing The Sensibility Of Various Photographic Sensitive Surfaces. There Are Various Forms, Which Are, However, All More Or Less Imperfect. The Reason Of This Is That A Standard Light Is Required, Perfectly Uniform, And Reproducible At Any Desired Place Or Time. A Light ...

Shellac
Shellac Mountant.—made By Dissolving One Ounce Of Shellac In Four Ounces Of Methylated Spirits, And Allowing To Stand For Some Time, When The Solution Will Be Ready For Use. Another Method Is To Dissolve The Shellac In A Hot Solution Of Borax And Water, But The Borax Is Liable To ...

Silver
Silver (symbol, Ag ; Atomic Weight, 108).—a White Metal Which When Quite Pure Is Rather Softer Than Gold, And Not Quite So Soft As Lead. It Is The Best Known Conductor Of Both Heat And Electricity. Its Great Use In Photography Is Due To The Fact That It Forms Compounds ...

Silver Bath
Silver Bath (for Paper).—in The Ordinary Method Of Making Photograph Positives By What Is Termed Silver Printing, Paper Prepared With Albumen Or Gelatine Containing A Certain Quantity Of A Soluble Chloride Is Floated For Varying Lengths Of Time On What Is Termed A "silver Bath." It Consists Of A Solution ...

Silver Bromide
Silver Bromide (formula, Agbr.; Molecular Weight, I88; Synonym, Bromide Of Silver).— Prepared By Direct Union Of The Two Elements Silver And Bromine, Or By Double Decomposition Between Silver Nitrate And Any Soluble Bromide. In The Daguerreotype Process, Silver Bromide Is Formed By The First Method, And In The Dry-plate Process ...

Silver Chloride
Silver Chloride (formula, Agci; Molecular Weight, 143.5; Synonyms, Chloride Of Sil Ver, Argentic Chloride).—a White Insoluble Substance Obtainable By Direct Union Between The Two Elements, Chlorine And Silver, Or By Double Decomposition Of Silver Nitrate With A Soluble Chloride. If A Solution Of Sodium Chloride Or Hydrochloric Acid Be Added ...

Silver Nitrate
Silver Nitrate (formula, Agno, ; Molecular Weight, Z7o ; Synonyms, Nitrate Of Silver, Argentic Nitrate, Lunar By Dissolving Pure Silver In Nitric Acid. Six Ounces Of Silver Are Dissolved In 2i Fluid Ounces Of Strong Nitric Acid And Zo Fluid Ounces Of Water, By The Aid Of Gentle Heat. The ...

Silver_2
Silver Tester.—an Apparatus For Testing The Quantity Of Silver Nitrate In Any Solution Pure Or Impure. For Ordinary Purposes The Argentometer Or Hydrometer Are Usually Used, The Specific Gravity Of The Liquid Determining The Amount Of Silver Nitrate Contained In It. When Working With The Silver Bath In Photographic Processes, ...

Snow Crystals
Snow Crystals, Photographing.—snow Crystals Evaporate Rapidly Even In Low Temperature, And The Work Requires To Be Done Rapidly And With Caution. Freshly Fallen Snow Only Will Give A Good Photograph, And As We Are Compelled To Work In The Midst Of The Snow Storm, The Task Becomes Still More Complicated ...

Sodium Citrate Restrainer
Sodium Citrate Restrainer. Citric Acid 720 Grains Sodium Bicarbonatef 884 Grains Distilled Water To Make 21z Ounces Of Solution. These Solutions Will Keep For An Indefinite Period, And Can Be Diluted By Adding Five Parts Of Water. The Advantage Of These Last Three Restrainers Is That When A Negative Shows ...

Sodium Hyposulphite
Sodium Hyposulphite (formula, + 511,0 ; Molecular Weight, 248 ; Synonyms, Sodium Thiosulphate, Hyposulphite Of Soda, By Passing Sulphurous Acid Gas Through Sodium Sulphide Until Sulphur Ceases To Precipitate, Or By Heating Sodium Sulphite With Excess Of Sulphur. It Takes The Form Of Irregular Crystaline Masses More Or Less Transparent. ...

Sodium Tunostate
Sodium Tunostate ( Formula, 2h ; Synonym Tungstate Of Soda, Molecular Weight, 317).—prepared By Fusing Wolfram With Sodium Carbonate. It Crystallizes In Rhomboidal Plates Soluble In Water, But Insoluble In Alcohol. It Is Principally Employed In The Toning Process. Soft Effects.—the Question Whether A Photograph Should Be Sharp All Over ...

Specific
Specific Uravity.—the Relative Weight Or Gravity Of Any Body Or Substance, Consid Ered With Regard To An Equal Bulk Of Some Other Body, Which Is Assumed As A Standard Of Com Parison. The Standard For The Specific Gravities Of Solids And Liquids Is Pure Distilled Water, At A Temperature Of ...

Specific
Specific Heat.—a Term Applied To The Quantity Of Heat Required To Raise Equal Weights Of Different Substances Through Equal Intervals Of Temperature. Water Is Taken As The Standard Substance In Measuring Quantities Of Heat. Spectroscope.—an Instrument Employed In Spectrum Analysis. It Usually Consists Of The Following Parts: (i.) A Tube ...

Squeegee A
Squeegee.--a Handy Contrivance Consisting Of A Strip Of Flat Indiarubber Set In A Wooden Back Or Handle. It Is Exceptionally Useful For Pressing The Front In Contact When Mounting For Carbon Printing, For Glazing Gelatine Prints, Etc., Where An Even Pressure Is Required. The India Rubber Should Be Neither Too ...

Standard
Standard Spirit.—a Mixture Of Alcohol And Water Having A Sp. Gr. Of '92 At 62 Deg. Fahr. It Contains Nearly Equal Parts Of Absolute Alcohol And Water. Stand, Camera.—see Camera Stand And Tripod. Stannotype.—this Process May Be Termed A Simplified Woodbury Process. On Refer Ence To The Description Of The ...

Stellar
Stellar Photooraphy.—see Asti-gnomical. Photography. Form Of Stereoscope Which Enables Reproductions Of Objects To Be Seen Stereoscopically, In Their Natural Colors. It Consists Primarily Of An Ordinary Stereo Scope, Such As Everybody Is Familiar With. The Two Stereoscopic Images, Placed Axially To The Oculars, Are Viewed By Means Of Colored Screens, ...

Stereoscopic
Stereoscopic Photooraphy.—the Art Of Stereoscopic Photography Was Practised Some Years Ago, And Held Public Attention For Some Twenty Years Or More, After Which It Gradu Ally Died Away. Many Attempts Have Of Late Been Made To Revive It, And It Is Quite Possible That With The New Appliances And The ...

Stripping
Stripping Film.—paper Coated First With A Solution Of Soluble Gelatine, And Then With A Sensitive Gelatine Emulsion As Used For Dry Plates. The Paper Acts As A Temporary Support During The Operations Of Exposure. Development, Fixing, And Washing, After Which The Film Is Laid Face Downwards On A Prepared Sheet ...

Stripping Films
Stripping Films (collodion).—negatives Produced By The Collodion Process Can Be Stripped From The Glass Support Without Much Difficulty. The Following Is The Modus Operandi : The Glass Plate Must Be Well Polished And Rubbed Over With French Chalk, And Then Polished Again. It Must Not Be Albumenized. When The Negative ...

Strontium Iodide
Strontium Iodide, (formula Yellowish-brown Needles, Soluble In Water And Alcohol. Sometimes Used As An Iodizer For Collodion. Studio.—the Old-fashioned Idea That Any Room With A Top And Side Light Constituted An Efficient Studio Has Long Since Been Abandoned, And Considerable Attention Is Now Paid By Photog Raphers In The Construction ...

Submarine
Submarine Photography.—what The Bottom Of The Sea Looks Like Is A Conundrum Which People Have Tried To Solve To The Best Of Their Ability During Recent Years. Of Course Pho Tography Has Been Called In To Render Its Valuable Assistance. What Has Been Done In This Direction Is Given By ...

Subterraneous
Subterraneous Photography.—the Chief Difficulty In Underground Photography Lies, As Would Naturally Be Imagined, In The Illumination. To Do This Satisfactorily By Artificial Means Requires Much Care And Thought. Mr. J. C. Bur Row, Writing Of His Experiences In Photographing The Workings Of A Cornwall Tin Mine Says " After Pre ...

Swing Back A
Swing Back.--a Contrivance At The Back Of A Camera Which Admits Of An Inclination Of Focusing Screen, Or Dark Slide, With Reference To The Axis Of The Lens. If The Swing Be Confined To One Plane It Is A Single Swing Back ; If Arranged To Move Upon Both A ...

Tannin
Tannin Process.—an Old Dry-collodion Process Invented By Major Russell. A Glass Plate Is First Well Cleaned With Tripoli Powder, And Then Washed In Clean Water And Dried With A Soft Cloth Previously Warmed. One Side Of The Plate Is Then Coated With The Following Gelatine Solution In The Same Manner ...

Telephotooraphic Lens A
Telephotooraphic Lens.--a Specially Constucted Lens Used In Telephotography, Q.v. Telephotooraphy.—the Combination Of The Telescope With The Photographic Camera. The Simplest Form Of Telephoto Lens Is The Ordinary Opera Glass. Mr. 0. G. Mason, In The Photo Graphic Times, Describes A Method Of Using This : He Says : "an Opera ...

Test
Test Tube.—a Thin Glass Tube With A Rounded Bottom Used In Making Tests. See Fig. 464. Test Tube-holder.—an Arrangement For Holding One Or More Test Tubes. See Fig. 465. Thermometer.—an Instrument For Measuring Intensity Of Heat Or Temperature By Means Of Expansion Of A Liquid Or Gas. Mercury Is Generally ...

Testing
Testing Lenses.—the Lens Being The Most Impor Tant Part Of The Photographer's Outfit It Is Advisable That This Should Be Perfectly Free From Defects Of All Kinds. Lenses By Well-known Makers Are Invariably Thoroughly Tested Before Being Sent Out. With Other Kinds, However, Some Rough And Ready Means Of Testing ...

Thiocarbamides Reversal
Thiocarbamides Reversal With.—it Has Recently Been Discovered That The Addi Tion Of A Thiocarbamide To The Developer Will Produce A Reversal Of The Image. The Following Remarks Upon The Subject Are By Professor Bothamley, F. I. C.* "phenyl-thiocarbamide Added In A Small Quantity To An Eikonogen Developer Containing Eikon Ogen ...

So Co
Co, + So, = Na,s0, + Co,. It Takes The Form Of Prismatic Crystals, Soluble In Four Times Its Weight Of Cold And Twice Its Weight Of Hot Water. Much Difficulty Has Been Experienced In Getting Pure Sodium Sulphite As Necessary For Pho Tographic Purposes, But Recently, However, Manufacturers Have ...