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Encyclopedic Dictionary of Photography

Acetic Acid
Acetic Acid (formula, C, 2 Weight, 6o. Synonyms, Purified Pyrolig Neous Acid, Methane Carboxylic Acid. Methyl Formic Acid, Formed By The Acetous Fermentation Of Alcohol. Acetic Acid Is A Monotonic Monobasic Acid, And Its Salts Are Termed Acetates. Alcohol, When Quite Pure, Is Not Affected By Exposure To The Air, ...

Acetylene
Acetylene (formula C,ii,).—an Illuminating Gas Obtained From Calcium Carbide When Brought Into Contact With Water. The Acetylene Is Evolved In Accordance With The Following Equation : Cac, H,0 = C,h, Cao Calcium Carbide Added To Water Forms Acetylene And Quick Lime. With This Reaction Great Heat Is Evolved And The ...

Acid Fixing
Acid Fixing Bath.—the Question As To Whether The Acid Fixing Bath Should Be Acid. Alkaline Or Neutral Is Still An Undecided One. Eder Was The First To Advise The Addition Of Sulphite Of Soda To The Hyposulphite Solution ; Others Preferred Carbonate Of Soda And Bisulphite. Dr. Higinson, After A ...

Actinic
Actinic Focus.—see Focus. Actinicism.—the Chemical Action Of Sunlight. See Actinic. Actinoqrapi1.—an Instrument Invented By Mr. Hunt For Regulating The Variations Of Chemical Influence On The Solar Rays ; Fully Described In The British Association Reports For The Name Has Also Been Given To A More Recent Invention Of Messrs. Hurter ...

Aerial
Aerial Photography.—in The Year /858 Nadar, Of Paris, Made Photographs From The Car Of A Balloon. A Balloon Camera For Obtaining Photo Graphs From A Great Height Was Invented And Patented By Woodbury In 1877. To A Captive Bal Loon Was Suspended A Camera, Fitted With A Rapid Lens And ...

Albumen
Albumen Process.—the Albumen Glass Positive Process Is Still Much Used For Making Transparencies, Lantern And Stereoscopic Slides. The Manipulations May Be Carried On In A Yellow Light, It Being More Pleasant To Work In Than The Red. First Prepare A Solution Of Albumen By Breaking Up Eggs Separately And Removing ...

Albumen Or
Albumen Or Albumin.—albumen Is The Chief And Characteristic Constituent Of The White Of Egg (albumen Ori) And Of The Serum Of Blood. Albumen Is Also Present In Many Other Animal And Vegetable Substances. Commercial Albumen Is Prepared Either From The White Of Egg Or From Blood Serum, The Colorless Liquid ...

Alcohol
Alcohol (formula, ; Molecular Weight, 46 ; Synonyms, Ethylic Alcohol, Aqua Vita', Spirits Of Is Obtained By Carefully Distilling Any Spirituous Or Fermented Liquor. If Wine Or Beer Be Placed In A Suitable Retort And Heat Applied, The Alcohol May Be Separated From The Less Volatile Matter, And Thus Obtained ...

Alpha
Alpha Paper.—a Name Given In England To A Printing Paper Coated With A Gelatine Film, In Which Is Contained A Combination Of Silver With A Chloride And A Bromide. It Is Used For Obtaining Positives By Artificial Light, And Is Subjected To Much The Same Treatment In Develop Ment As ...

Aluminium Sulphate
Aluminium Sulphate (formula Al 3(so, ), 8h 0.)—formed By Dissolving Aluminium Hydroxide Or Sulphuric Acid. It Is Sometimes Recommended As A Substitute For Alum For Hardening Gelatine Prints And Emulsions. Dictionary Meaning Of The Word Amateur Is "one Who Follows Any Science, Art Or Occupation, Not From Pecuniary Motives, But ...

Amber
Amber (synonym, Fossil Resin From An Extinct Pine, Pinites Succinifer. A Hard Brittle Substance, Generally Yellow, But Sometimes Reddish-brown Or Whitish And Clouded. The Chief Supplies Come From The Baltic. It Is Used For Preparing A Varnish, Being Soluble In Chloroform Or Ether. See Varnish. Ambrotype..—an Old Term For A ...

Ammonia
Ammonia (formula, Nh,; Atomic Weight, 17.oi. Synonyms, Spirits Of Hartshorn, Vola Tile Name Is Supposed To Be Derived From Ammonia, The District Of Libya, Where It Was First Prepared, Or From Its Being First Manufactured From Camel's Dung Collected By The Arabs At The Temple Of Jupiter Ammon In The ...

Analysis
Analysis.- In Chemistry, The Examination Of Bodies With A View Of Ascertaining Of What Substances They Are Composed And In What Proportions These Substances Are Contained. The Former Is Termed Qualitative And The Latter Quantitative Analysis. There Are Various Methods Of Analyzing Or Separating The Particles Of A Chemical Compound. ...

Anat1orphosope
Anat1orphosope. — An Optical Toy, Consisting Usually Of A Vertical Cylindrical Mirror In Which A Distorted Drawing Or Anamorphosis. Anatiorphosis.—the Name Anamorphosis Has Been Given To Two Sorts Of Pictures, Dis Torted According To A Certain Law, And Which Are Of Such A Grotesque Appearance That It Is Often Impossible ...

Angle
Angle, Wide.—" Wide Angle" Is A Term Applied To Certain Forms Of Lenses So Constructed That They Will Embrace A Larger Amount Of View Than The Ordinary Or Narrow Angle Lens By Having Their Focus Very Short In Comparison To The Base Line Of The Plate. Figs. 31 And 32 ...

Aniline
Aniline Process Based On The Oxidation Of Aniline By Chromic Acid, And Used For Copying Tracings, Maps, Etc., Invented By Willis. Paper Is Sensitized With A Solution Consisting Of Potassium Dichromate T Part, Phosphoric Acid (sp. Gr. Z.124) 8 To Io Parts, And Water O To 1 2 Parts. This ...

Applications Photography
Photography, Applications Of.—the Introduction Of The Modern Dry-plate Process, And Consequently The Reduction Of The Time Of Exposure To Fractions Of A Second, Has Caused Photography To Be Of Great And Wonderful Assistance To Nearly All The Modern Arts And Sciences. Perhaps The Science That Has Mostly Benefited Has Been ...

Architectural
Architectural Photography.—in Photographing Architecture (where Parallel, Vertical, And Horizontal Lines Are Included), It Is Essential That A Lens Be Used That Gives The Least Amount Of Distortion. It Is Clear, Then, That A Landscape Or Single Combination Lens Is Unsuited For The Purpose. The Best Results Are Obtained With A ...

Argentic
Argentic Salts.—silver Salts, Such As Argentic Chloride, Argentic Nitrate, Etc. See Silver Chloride, Silver Nitrate. Arcentometer.—an Instrument For Measuring The Quantity Of Silver Nitrate Contained In An Aqueous Solution By Its Specific Gravity. It Consists Of A Simple Hydrometer Marked With A Scale Showing The Number Of Grains Of Silver ...

Artiques
Artique's Proce55.—a Process For Reproducing Plans, Drawings, Etc. It Is Practi Cally A Modification Of The Carbon Process, And Is Thus Described :* " The Paper Can Be Prepared With Any One Of The Following Solutions : Ist. Dissolve 2 Parts Of Ammonium Bichromatic And 5 Parts Of Best Gum ...

Asphaltum
Asphaltum (synonyms, Asphalt, Bitumen, Bitumen Of Judea, Mineral Pitch, And Jew's Natural Product Of The Decomposition Of Vegetable Substances. It Is Found On The Shores Of The Dead Sea, Also In A Molten State In Trinidad, And As A Mineral Deposit At Seyssel. Small Quantities Have Been Found In Derbyshire, ...

Auxiliary
Auxiliary Exposure.—the Sensitive Dry-plate, Either Before Or After Exposure In The Camera, Is Exposed For A Fraction Of A Second To A Weak, Diffused Light. This Method Has Been Several Times Recommended By Competent Authorities For Under-exposed Negatives, And Softer Effects Are Stated To Be The Result. Auxometer.—an Instrument To ...

Bain Marie Or Balneum
Bain Marie Or Balneum Waterbath. The Substance To Be Heated Being Placed In A Proper Vessel, The Latter Is Placed Into Another Vessel Containing Water And Capable Of Stand Ing The Application Of Fire By Which Heat Is Gradually Communi Cated. An Arrangement Of This Kind, As Shown In Fig. ...

Barium Saccharate
Barium Saccharate (formula, Ba0c, ).—barium Saccharate Is Sold As A White Crystalline Powder, Soluble In Water, And Poisonous. It Is Sometimes Employed As An Alkali In Development. Barometer.—an Instrument For Estimating The Weight Or Pressure Of The Atmosphere, Invented By Torricelli In 1643. Torricelli Discovered That If A Tube Closed ...

Baryta
Baryta Paper.—a Paper Prepared With Baryta, Or Barium Chloride, And Coloring Matter. It Has A Fine, Smooth Surface, And Is Largely Used In Collotype Printing. This Paper Is Also Employed In The Aristotype Process, As It Offers A Smooth Surface For The Gelatine Or Collodion Emulsion, Prevents It From Sinking ...

Beecheys
Beechey's Process.—an Unwashed Collodion Emulsion Process Introduced By Canon Beechey. The Following Is The Simple And Efficient Modus Operandi : Cadmium Bromide (anhydrous) 200 Grains Alcohol (.8o5). 5 Ounces Are Placed In A Bottle And Allowed To Stand For Some Hours. The Solution Thus Formed Is Then Carefully Decanted, And ...

Belitzkis Reducer For Gelatine
Belitzki's Reducer For Gelatine Plates. Water 7 Ounces Potassium Ferric Oxalate 24 Drachms Crystallized Neutral Sodium Sulphite 2 Drachms Powdered Oxalic Acid 3o To 45 Grains Sodium Hyposulphite 14 Ounce The Solution Should Be Made Up With The Ingredients Added In The Same Order As Written. It Is Then Filtered ...

Bichromate
Bichromate Disease.—a Cutaneous Disease Produced By Prolonged And Frequent Handling Of Potassium Dichromate, Whether Dry Or In Solution, Or By Allowing The Solution To Enter A Scratch Or Abrasion Of The Skin. In The First Case It Takes The Form Of A Thick Red Rash, Which, If Closely Examined, Shows ...

Bottles
Bottles. —the Selection Of Conven Ient Bottles For The Various Chemicals Used In Photography Requires Some Little Thought. Acids Should Be Kept In Glass-stoppered Bot Tles (fig. 73), And The Stoppers Rubbed Round With A Little Vaseline. This Renders The Stop Per Perfectly Air-tight, And Prevents It From Becoming Fast ...

Broken
Broken Neoative.—with A Little Care And Trouble Passable Prints May Be Made From Broken Negatives If The Glass Only Is Cracked Or Broken. If The Film Is Broken, However, It Is Almost Useless To Endeavor To Hide The Defect. Even With A Cracked Negative It Is Usually Less Trouble To ...

Bromide
Bromide Paper.—a Paper Coated With A Gelatino-bromide Of Silver (described Under Emulsion, Q.v.) And Used For Enlargements Or Printing By Contact. This Paper, Of Which There Are Several Kinds, May Be Obtained Having A Smooth Or A Rough Surface, The Latter Being Most Suitable For Enlargements. It Should Be Mentioned ...

Camera
Camera Obscura.—an Instrument In Which, As Its Nam Eimplies, The Essential Feature Is A Dark Chamber. It Is Said To Have Been Invented By John Baptista Porta, A Neapol Itan Philosopher. But Although A Description Of The Instru Ment Is Given In His " Seventeenth Book Of Natural Magick, Wherein ...

Carbon
Carbon Tissue.—paper Coated With Gelatine Containing One Or More Pigments, And Used In The Carbon Process, Q.v. The Composition Of The Pigments Used Should Be Carefully Studied. If Carbon Lampblack Only Is Used, We Get Pictures That Will Last A Long Time, As Proved By The Brilliancy Of Printers' Ink ...

Carbon Process
Carbon Process (synonym, Process Based Upon The Fact That Gelatine And Other Organic Substances, If Heated With A Bichromate, Become Sensitive To Light Which Renders Them Insoluble In The Parts Exposed. This Fact Was Discovered By Mungo Ponton In 1838, But It Is To The Subsequent Discoveries And Improvements Of ...

Caricature
Caricature Photoorapt1.—a Photograph In From Timandler's Handbook. Which The Natural Characteristics Of A Person Or Object Are Fig. 96.—caricature Portrait. Exaggerated Or Distorted. There Are Quite A Number Of Different Methods Of Making Caricature Portraits. A Simple One Is To Make Two Photographs Of An Individual. One Of The Head ...

Chemical
Chemical Focus.—a Lens Possesses Two Foci, The Visual And The Chemical. Before The Many Improvements In Optical Instruments Were Made These Two Foci Differed ; In Some Cases Very Considerably, So That It Was Necessary To Determine The Difference, And After Focusing On The Screen At The Visual Focus, To ...

Chlor0 10do Bromide
Chlor0-10do-bromide Emulsion.—an Emulsion Containing A Chloride, An Iodide, And A Bromide. Chlorophyl.—the Peculiar Substance To Which The Green Color Of The Leaves, Fruit And Other Parts Of Plants Is Due, And The Nature Of Which, Notwithstanding The Extent Of The Researches That Have Been Made, Is Still Doubtful. It Dissolves ...

Chlorine
Chlorine (symbol Cl. Atomic, Weight 35.5 ).—the Elementary Substances, Chlorine, Bro Mine, Iodine And Fluorine, Are Called Halogens, Because They Produce With Other Elementary Sub Stances Bodies Resembling Almost In Every Respect The So-called Oxysalts. Cyanogen, A Compound Radical, Is Often Likened To The True Halogens On Account Of It ...

Chloro Bromide
Chloro-bromide Emulsion.—an Emulsion Containing Both A Chloride And A Bromide. Chloroforrl (formula, Ch ; Molecular Weight, 119.52 ; Synonyms, Methenyl Chloride, Formyl Is Prepared By The Distillation Of A Mixture Containing Bleaching Powder, Slacked Lime, Water, And Alcohol. The Alcohol And Water Are Added Together And Warmed In A Still ...

Chrono Photography
Chrono-photography (synonym, Photo-chronography).—a Term Applied To The Photography Of Objects Or Animals In Motion At Regular Intervals Of Time. Muybridge, Dickson, Edison And Jenkins Of This Country, Marey Of Paris, And Anschtitz Of Lissa, Have Made A Special Study Of Chronophotography, And The Value Of Their Researches In The Science ...

Citric Acid
Citric Acid (formula, + H 0 ; Molecular Weight, 2m).—an Acid Which Occurs In Lemons, Oranges, Cranberries, And Also With Malic Acid In Gooseberries, Whortleberries, Rasp Berries, Etc. It Also Occurs In Many Plants And Roots. It Is Obtained By Allowing The Juice To Undergo An Incipient Fermentation, Fil Tered, ...

Coal
Coal Tar.—a Tar Produced In The Destructive Distillation Of Bitumenous Coal, And From Which Many Of The Aniline Colors—napthalene, Phenol, Etc.—are Prepared. Coating.—the Term Is Largely Used In Photography To Define The Act Of Covering Glass, Paper, Etc., With A Film Of Any Kind. In The Dry-plate Process The Glass ...

Coffee
Coffee Process.—a Number Of Modifications Have Been Made Of This Process, The Best Being Perhaps That Of M. De Constant. Abney's Description Of This Process Is As Follows: The Collodion To Be Recommended For This Process, According To M. De Constant, Is Ordinary Collodion, With The Addition Of Two Grains ...

Collodio Chloride
Collodio-chloride Emulsion.—in This A Chloride Is Substituted For The Bromide Usually Used In The Manufacture Of Collodion Emulsions. It Must Be Pointed Out That There Are Two Kinds Of Collodio-chloride Emulsions Used For Different Purposes—the One In Which The Image Is Developed, And The Other In Which It Is Printed ...

Collodio Chloride Printing Out
Collodio-chloride Printing-out Process.—• Silver Printing Process In Which Collodion Is Used As The Article To Hold The Silver Salts. The Name Aristotype Has Also Been Applied To This Process As Well As To Its Sister Process, The Gelatino-chloride. It Is Also Termed Collodion Paper. The Earliest Experiments In Collodio Chloride ...

Collodio Gelatine
Collodio-gelatine Process,—a Process Patented In 1856 By Dr. Norris. In This The Collodion Film, Containing The Sensitive Silver Salts, Was Immersed In A Solution Of Gelatine, Albu Men, Caseine, Or Any Other Similar Substance. The Object Of This Was To Fill Up The Pores Of The Collodion Film And Prevent ...

Collodion Albumen
Collodion-albumen Emulsion.—a Collodio-albumen Emulsion. A Process Intro Duced By Captain Abney, And Thus Described By Him. The Following Is The Mode Of Preparation: Sixteen Grains Of Ordinary Cotton Are Dissolved In 6 Drachms Of Ether (.730) And 4 Of Alcohol (.805), And The Plain Collodion Thus Formed Decanted. Twenty Grains ...

Collodion Dry Plate
Collodion Dry-plate Process.—the First Published Practical Formula For A Collodion Emulsion Was That By Messrs. Bolton And Sayce In 1864. With This Process A Dry Collodion Emulsion Is Used, And Before Going Farther It Will Perhaps Be Best To Explain The Difference Between The Collodion " Dry" And The Collodion ...

Collodion Emulsion
Collodion Emulsion (washed).—a Plain Collodion Is First Made Up After The Following Formula : Alcohol, .82o 5 Ounces Ether, .72o. Zo Ounces Pyroxylin 200 Grs. If A Plain Collodion, As Sold By Dealers, Be Used It Should Be Remembered That The Amount Of Bromide Silver Should Be Regulated According To ...

Collodion Emulsion_2
Collodion Emulsion (unwashed). – In This Procegs The Emulsion Is Not Washed Until After The Plates Are Coated. The First Operation Is The Manufacture Of The Collodion, Which Is Done After The Following Formula : Sulphuric Ether (.72o) 7 Ounces Alcohol (.820) 4 Ounces Pyroxyline (high Temperature) 7o Grains Zinc ...

Collodion Epiulsion
Collodion Epiulsion Proce55.—it Is Intended Under This Heading To Describe The Preparation And Manipulations Of The Dry Collodion Plates. In Other Places It Has Been Pointed Out That There Are Two Distinct Methods Of Preparing The Emulsion—the One Termed The "washed " Emulsion Process, And The Other The " Unwashed ...

Collodion Wet
Collodion Wet Process.—a Process In Which Collodion Forms The Vehicle To Hold The Sensitive Salts. It Is Commonly Known As The Wet-plate Process, In Contradistinction To The Dry-plate Process, The Film Being Exposed In The One Case Whilst Wet And In The Other When Dry. Before Describing The Process In ...

Collodion Wet Process For
Collodion Wet Process For Positives.—very Little Difference In The Manipula Tion Is Necessary For The Production Of Positives By The Wet Process Than For Negatives As Described Under Collo Lion Wet Process. The Chief Object Is To Obtain The Deposit Of Silver As White As Possible. The Collodion Is The ...

Colored
Colored Photographs.—by Colored Photographs Is Meant The Production Of Photo Graphs Colored By Artificial Means, And Not The Making Of Photographs In Natural Colors—a Process Not Yet Accomplished Except By Very Unsatisfactory Means. There Are Various Methods Of Coloring Photographs Which May Briefly Be Divided Under Two Headings—the Application Of ...

Conjugate
Conjugate Foci.—a Lens Has Two Foci Having A Definite Relation To Each Other, And Are, Therefore, Termed The " Conjugate Foci." See Focus. Besides The Equivalent Focus Of The Lens, Which Should Be Known By The Worker, It Is Often Useful To Know—ist, The Size Of The Image That Will ...

Coopers
Cooper's Process.—a Printing Process, The Invention Of Mr. Henry Cooper The Basis Of The Process Lies In The Substitution Of A Resin Or Substance Of A Resinous Nature, In The Place Of Albumen Or Other Sizing Matter. Prints Obtained By This Process Have A More Artistic Appearance Than Pictures Printed ...

Copper
Copper Sulphides.—there Are Two Distinct Sulphides Of Copper Which May Be Pre Pared. Copper And Sulphide, When Melted Together, Combine With Vivid Incandescence, And Produce The Subsulphide (cuprous Sulphide), Cu, S. Cupric Sulphide Is Found Native As Covellite, But Can Be Artificially Prepared By Precipitating A Salt Of Copper With ...

Daiimar
Daiimar (malay Damar).—a Pale Yellow Or White Resin Obtained From The Dammara Australis, Commonly Known As The Kawrie Or Cowdie Pine In New Zealand, And The Damnzara Alba, Dammar Pine, Or Cat's-eye Resin Of India. Dammar Resin Is Also Obtained From The Amborgna Pine Growing In The Malay Archipelago. It ...

Dark Slide
Dark Slide, The English Term For The Plate Holder. It Is Also Termed The Single Or Double Back. The Double Backs Are The Most Convenient, As They Carry Two Plates In But Little Larger Space Than Required For One. The Dark Slide, Usually Made Of Wood Or Metal, Must Be ...

Detective
Detective Camera.—see ' Detergent—any Substance Possessing The Property Of Cleansing. Alkalies Have The Power Of Dissolving Both Soap And Grease, Hence Both Are Used As Detergents. For Cleansing Glass The Agents Used Are Generally Tripoli Powder, Ammonia, Alcohol, Caustic Soda, Potash And Diluted Acids. A Solution Of Potassium Dichromate D ...

Developing
Developing Tubes.—glass Tubes With Closed Ends, One Containing Pyro And The Other Ammonia. They Are Made For The Convenience Of Tourists. Iarhen Required For Use The Ends Are Broken Off And The Solutions Mixed With The Proper Quantities Of Water. Development.—the Process Of Rendering The Latent Image Visible By Means ...

Diaphanoscope
Diaphanoscope —a Dark Box For Exhibiting Transparent Pictures With Or Without A Lens. The Positive Should Be Placed In The Box At A Distance From The Eye Equivalent To The Focal Length Of The Lens With Which The Negative Was Made. Diaphragm.—these Are Metal Plates, With A Hole In The ...

Dissolving
Dissolving Views.—see Magic Lantern. Distance.—the Extreme Boundary Of View In A Picture, That Part Which Appears Farthest From The Eye. In Perspective The Point Of Distance Is That Point Of A Picture Where The Visual Rays Meet. The Middle Distance Is The Central Part Of The Picture, And The Line ...

Distilled
Distilled Water.—(formula Molecular Weight, Z8.)—pure Water Obtained By Distillation. In All Delicate And Important Photographic Operations Distilled Water Should Be Used. Pure Distilled Water Should Give No Precipitate With Agno, Showing Absence Of Any Chloride; Nor With Ammonia Oxalate, Which Would Otherwise Show The Presence Of Lime; Nor With Barium ...

Dry Collodion
Dry Collodion Process.—see Collodion Emulsion Process. Dry Distillation.—see Destruct Ive Distillation. Dry-plates.—plates Of Glass Of Dif Ferent Sizes, Coated With A Film Of Gelatine In Which A Sensitive Silver Salt Is Emulsified. Dry Plates Are Now Manufactured In Such Large Quantities That It Is Rarely Beneficial To Either Amateur Or ...

Electric
Electric Electric Light Is Now Used In Many Large Photographic Works, And In A Few Studios For Portraiture. For Enlarging And Printing It Is Now Much Used. The Heavy Outlay In An Electric Installation Is, However, The Chief Drawback To Its More Universal Use. For Portraiture At Night The Electric ...

Explosive
Explosive Powder.—a Powder Used In The Flast-light Process Of Illuminating During Exposure. (see Flash-light.) Exposure.—by Exposure Is Meant The Exposure To The Action Of Light Any Sensitive Sur Face, Either In The Camera To The Image Formed By The Lens, Or Behind A Negative In A Printing Frame. The Exposure ...

Fig 127 M Machs
Fig. 127 -m. Mach's Api'ar Atus. A Chemically Clean Piece Of Glass In As Many Hours. Cleaning Are Many Methods Of Cleaning A Glass Plate Successfully. The Application Of Tripoli Powder Solution, Rubbed Well Over The Surfaces With A Piece Of Old Rag, Is One To Be Recommended. This Is ...

Fluorine
Fluorine (symbol, F; Atomic Weight, I9i).—a Non-metallic Element, Only Recently Obtained In A Free State. It Is An Isometric, Transparent Mineral Usually Obtained From Fluor Spar. Principal A Pencil Of Parallel Rays Enter A Convergent Lens, They Will Be Brought Together At A Point F (fig. 192) On The Other ...

Focus Adjuster
Focus Adjuster.- .an Arrangement Fitted To A Lens, And By Means Of Which The Focus Can Be Adjusted To Different Lengths For Various Purposes. Traill Taylor In His Work On Photo Graphic Optics There Describes A Convenient Form Devised By Himself. It Consists In A Sliding Piece Of Brass Made ...

Focusing
Focusing Screen.— The Material Upon Which The Image Formed By The Lens Is Seen. This Is Usu Ally A Piece Of Ground Glass Of The Best Quality. It Can Be Made By Grinding A Piece Of Patent Plate Glass With Very Fine Emery Pow Der. The Most Convenient Plan Is ...

For Washed Emulsion
For Washed Emulsion (for Transparencies). Ether, S.g. .720 5 Fluid Ounces Alcohol, S.g. .820 3 Fluid Ounces Pyroxyline Or Papyroxyline 6o Grains Bromide Of Cadmium And Ammonium Too Grams Or Bromide Of Zinc 96 Grains • Hydrochloric Acid, S.g. 1.2 8 Minims Sensitize With Twenty Grains Of Nitrate Of Silver ...