Juices Of Plants
Juices Of Plants. Papers Stained With The Juices Of Various Plants Are Altered In Colour By Exposure To Sunshine. Sir John Herschel, Some Years Ago, Communicated To The Royal Society The Results Of Many Interesting Experiments Made By Him On The Juices Of Plants. His Method Of Proceeding Was, To ...
Lac
Lac. A Species Of Resin Secreted From The Puncture Made By An Insect Called The Coma Flew, In The Branches Of Various Plants Which Grow In The East Indies. Lac Is A Very Important Article In Manufactures, Because Not Only Is The Resin Useful For Making Varnishes, Sealing Wax, 8r,c., ...
Latent Heat Latent Light
Latent Heat. Latent Light. It Is Stated In The Article On Light, That Both Light And Heat Are Certainly Due To The Undulations Of An Elastic Ether Which Pervades Space ; And That The Rays, Both Of Light And Heat Are Propagated With Enormous Velocity, And Can Be Refracted, Reflected, ...
Leather
Leather. An Insoluble Compound Of Tannin And Gelatine. Tannin Is A Very Delicate Test Of Gelatine, And If Added To Water Containing The One Five-thousandth Part Of Gelatine It Produces A Cloudiness In It. It Combines So Energetically With Gelatine, That If A Piece Of Skin Or Bladder Of Sufficient ...
Lens
Lens. A Lens Is A Transparent Body Constructed For The Purpose Either Of Concentrating Or Scattering Rays Of Light Transmitted Through It. Lenses Are In General Made Of Glass Or Rock Crystal, And Ground With Spherical Surfaces ; The Axis Of The Lens Being The Line Joining The Centres Of ...
Light
Light, Therefore, Is Motion ; Or Shall We Say That Light Is The Means By Which A Blow Is Transmitted From The Luminous Body To The Body Upon Which Light Is Incident. Light Travels In Vacuo With Uniform Velocity ; But There Are Different Kinds Of Light, That Is, Light ...
Light
Light. What Is Light P Why Does It Render Objects Visible, Exhibit Different Colours, Produce Chemical Changes In Bodies, And So Forth ? These Are Questions Of The Highest Importance In Science, And Of Especial Interest To The Photographer. We Shall Endeavour Briefly To Explain In The Present Article What ...
Lion In
Lion In ; This Substance May Be Considered As A Compound Of Carbon And Water. It Is Of Great Importance In Photography, First Because Pyroxyline Is Made From It, And Secondly Because Paper Is A Nearly Pure Form Of It. Lignin Forms The Solid Framework Of Plants. It Is Obtained ...
M Petzvals Portrait Combination
M. Petzval's Portrait Combination. The Object Of This Instrument Is To Obtain An Image Well Defined In Its Principal Parts, When A Large Volume Of Light Ic Admitted. In Taking A Portrait It Is Evident That The Time Of Exposure Should Be Reduced As Much As Possible, Because After Remaining ...
Magic Lantern
Magic Lantern. An Instrument For Exhibiting Magnified Images Of Transparent Pictures Upon A Screen. The Arrangement Of The Different Parts Of The Apparatus Will Be Understood From The Following Figure. A Is The Source Of Light ; Which May Be Either An Argand Lamp With A Reflector Behind It, Or ...
Micro Photography
Micro-photography. Under This Head May Be Included Two Different Processes. One Is Of Little Or No Practical Utility, And Con Sists In Copying Objects On An Exceedingly Small Scale, The Photograph Being Intended To Be Viewed Tlrough A Magnifier, Or Microscope. The Other, Which Is A Branch Of Photography Of ...
Moedant
Moedant. A Class Of Substances Used In Dyeing, Their Effect Being To Cause The Dyeing Material To Combine With The Fabric To Which It Is Applied, So That It Cannot Be Removed By Simple Washing, Or Any Ordinary Treatment. Mordants Are In General Metallic Oxides Which Have An Affinity For ...
Mounting Prints
Mounting Prints. This Consists In Attaching The Print, Either Entirely, Or By Its Edges, To A Sheet Of Cardboard, By Means Of An Adhesive Cement. Of All Adhesive Substances, Starch Appears To Be The Most Suitable. It Should Not Be Made Too Thick, And After Being Boiled Should Be Strained ...
N06 Nitrate Of Potass
Nitrate Of Potass ; Nitre ; Saltpetre. Ko, N06. This Important Salt Is Obtained In India In Large Quantities, But In An Impure Form, By Lixiviating Certain Soils ; And In France, And Other Countries, It Is Obtained From Old Mortar Rubbish, In Which Organic Matter Has Supplied The Nitrogen ...
Nitrate Bath
Nitrate Bath. Many Of The Failures In Photographic Opera Tions, Particularly In The Negative Collodion Process, May Be Traced To The Nitrate Bath Being Out Of Order. 1st. It May Not Be Of The Right Strength. Test It With The Silver Meter (q. V.), And Add Either Water Or Nitrate ...
Nitrate Of Silver
Nitrate Of Silver. Ag. 0, = 170. This Is One Of The Most Important Salts At Present Used In Photography. , It Is Obtained In Its Purest Form By Dissolving Pure Silver In Pure Nitric Acid, S. G. 1.25, Evaporating And Crystallizing, And Then Redissolv Ing And Recrystallizing. The Salt ...
Optical Centre
Optical Centre. Every Single Lens Has A Certain Point Called Its Optical Centre ; No Such Point, However, Exists In The Case Of An Achromatic Lens, Or Combination Of Lenses. This Should Be Distinctly Understood, Because Ignorant Persons Frequently Commit The Blunder Of Speaking Of The Optical Centre Of A ...
Other Surfaces
Other Surfaces. This Part Of Photographic Manipulation Is One Of Some Importance. The Production Of Uniform Films By Means Of Vapours Is Very Simple In Execution, But It Is Doubtful In Such Cases As The Daguerreotype, What Is The Exact Composition Of The Sub Stances Formed. Their Continual Change Of ...
Oxide Of Iron
Iron, Oxide Of. There Are Four Definite Oxides Of Iron Viz : The Protoxide . . . Fe. 0 Sesquioxide. . . Black Oxide . . Ferric Acid . . . The Salts Of The Sesquioxide Of Iron Are In General Converted Into Salts Of The Protoxide By The Action ...
Oxide Of Silver
Silver, Oxide Of. There Are Three Oxides Of Silver, Viz. Suboxide 0 Protoxide . A G 0 Binoxidt A G 02 Of These The Protoxide Only Forms Salts. Suboxide Of Silver Is Produced As A Grey Film When Ammonio Nitrate Of Silver Is Exposed To Air. It Is Also Produced ...
Oxygen 08
Oxygen. 0=8. (greek Ovc Sharp, Yevretv To Produce.) An Elementary Gas, The Name Of Which Is Derived From Its Property Of Pro Ducing Acids. The Atmosphere Contains About One-fifth Part, By Volume, Of Oxygen Gas, In A State Of Mixture ; And 'water Eight-ninths, By Weight, In Combination With Hydrogen. ...
Panoramic Camera
Panoramic Camera. This Is A Form Of Camera Invented By The Author, In Which Pictures May Be Taken Upon One Flat Plate, Including An Angle Of 90°, Or More If Required, Without Introducing The Defects Due To Oblique Pencils, Such As Distortion, Indistinct Ness, &c. The Following Figure Will, It ...
Paper Making
Paper-making. Paper May Be Made Of Any Prow Material Which Can Be Torn And Beaten Into Pulp. The Substances Commonly Employed Are Linen And Cotton Rags, And For Coarser Kinds Of Paper, Grass And Straw. We C,annot In This Work Go At Any Length Into The Process Of Paper-making, But ...
Perspective
Perspective. There Are Two Kinds Of Perspective Delineation With Which The Photographer Is Concerned, Viz., " Plane," And " Panoramic Perspective.' In Plane Perspective, Objects Are Represented Upon A Vertical Plane Placed Between Them And The Spectator. Straight Lines, Called " Visual Rays," Are Supposed To Be Drawn From The ...
Phosphori
Phosphori. Bodies Which Emit Light In The Dark, After Having Been Exposed To Light, Are Called " Solar Phosphori." When We Consider That Bodies Which Have Been Exposed To Heat Continue To Radiate Heat For Some Time After Being Removed From The Source Of Heat, And That Heat And Light ...
Phosphorus P32
Phosphorus. P=32. This Remarkable Elementary Body Is Contained In The Bones And Fluids Of Animals, And Also In The Vege Table And Mineral Kingdoms. In Bones It Exists As Phosphate Of Lime, And Is Obtained From Them By Acting On Calcined Bones With Sulphuric Acid, And Distilling The Superphosphate Of ...
Photo Lithography
Photo-lithography. This Process, Like The Last, Is In A Some What Imperfect State, But It Will No Doubt Receive Further Development And Become Eventually Of Much Practical Utility. It Consists In Pro Ducing From A Negative A Positive Upon Stone Which Will Take Printers' Ink, And May Be Printed From ...
Photographic Engraving Upon Wood
Wood, Photographic Engraving Upon. The Wood Engraver Would In Many Cases Derive Valuable Help From Photography, If Positive Prints Could Be Obtained Upon The Surface Of Wooden Blocks Without Injury To The Texture Of The Wood. The Following Proce,ss, Which Appears To Be The Best At Present Known, Is Extracted ...
Pigments
Pigments. Positive Prints May Now Be Obtained In Various Pig Ments, By Mixing Them With An Organic Substance, And Bichromate Of Potass,—applying The Mixture Evenly To The Entire Surface Of A Sheet Of Paper, Drying It, And Exposing It Under A Negative,—then Washing It In Water Or A Suitable Solvent, ...
Plate Glass
Plate Glass. This Is Made Of The Same Materials As Crown Glass, And Does Not Contain Lead. Vast Quantities Of It Are Now Used In Photography. Plate Glass Is Made By Pouring A Quantity Of The Fused " Metal ' Upon A Table Or Cuvette Of Cast Iron, And Then ...
Portrait
Portrait Room. The Construction Of The Room In Which Portraits Are Taken Is A Matter Of The First Importance. The Best Arrangement For Producing A Pleasing Expression In The Countenance Of The Sitter, An Artistic Effect Of Light And Shade, And A Portrait Free From Distortion And Disagreeable Exaggeration Of ...
Positive Collodion Process
Positive Collodion Process. By This Process, A Direct Positive Is Produced On A Collodionized Tablet, By Developing The Image That Is Obtained In The Camera. The Collodion Positive And Negative Processes Differ In The Following Important Particular, Viz : In The Negative Process The Object Is To Obtain A Picture, ...
Preservative Processes
Preservative Processes. The Object Of These Processes Is To Preserve The Sensitiveness Of An Excited Collodion Plate For A Longer Or Shorter Time, As May Be Required, And Thereby To Do Away With The Inconvenience Of Preparing The Plate And Developing The Picture On The Spot Whence The View Is ...
Printing Process
Printing Process. By " Printing " Is Meant The Reproducing A Positive, In Which The Lights And Shades Are True To Nature, From A Negative In Which They Are Reversed. The Operation Not Being At Tended With The Destruction Of Or Injury To The Negative May Be Repeated Indefinitely, And ...
Prism
Prism. In Solid Geometry A Prism Is A Solid Described By The Motion Of A Straight Line Which In Passing Round The Boundary Of A Plane Rectilineal Figure Always Preserves Its Parallelism, The Solid Being Terminated At The Other Extremity By A Plain Figure Parallel To The First. In Optics, ...
Pyboxyline
Pyboxyline. This Substance, Which When Dissolved In Ether Forms Collodion, Is Made By Acting On Lignin With A Diluted Mixture Of Sulphuric And Nitric Acids Represented By The Formula Ho, Ho, Ho, The Temperature Being Uniformly Maintained At From To According To The Quality Of The Collodion Required. It May ...
Reflecting Prism
Reflecting Prism. Suppose F Gh To Be A Glass Prism Having Equal Sides Fg, Gh, And The Angle At G A Right Angle ; And Let Ab Be A Ray Of Light Incident At B Perpendicularly To The Side Gh. This Ray Vrill Not Suffer Deviation On Entering The Glass, ...
Reflexion At A Plane
Reflexion At A Plane Surface. When A Virtual Imag,e Of Luminous Object Is Formed By Reflexion At A Plane Surface, There Is No Spherical Aberration In The Pencils, Nor Any Distortion In The Image, And The Imag,e Is Situat,ed In Exactly The Same Relative Position With Respect To The Reflector, ...
Refraction
Refraction. When A Ray Of Light Passes Out Of One Transparent Medium Into Another Of Different Density It Is Bent Out Of Its Course, And Suffers Deviation. The Law Is, That The Refracted Ray Lies In The Same Plane With The Incident Ray And The Normal To The Surface At ...
Seed Lac
Seed Lac. See "lac." Seed-lac Is Said To Be More Soluble In Alcohol Than Shellac, And Therefore To Make Clearer Varnish. A A 2 Sel D'olt. All. 0, S2 02 + 3 [na. 0, S2 02] + 4 H O. This Salt Is A Double Hyposulphite Of Gold And Soda, ...
Silver Meter
Silver-meter. This Is An Instrument For Testing Accurately The Quantity Of Nitrate Of Silver In An Old Nitrate Bath Containing Impur Ities Which Affect The S. G. Of The Liquid, And Therefore Render The Hydrometer Useless As A Means Of Testing Its Strength In Silver. The Principle On Which This ...
Specific Heat
Specific Heat. By The Specific Heat Of A Body Is Meant The Time It Takes To Cool From A Certain Given Temperature To Another Given Temperature, When Placed In Vacuo In A Polished Silver Vessel. By Some Writers The Specific Heat Of A Body Is Supposed To Be Its " ...
Spectrum
Spectrum. Suppose A Small Hole Of Any Shape Made In The Window Shutter Of A Darkened Room, And That Sunshine Be Ad Mitted Through It, And The Light Received Upon A White Screen, Placed Perpendicularly To The Line Joining It And The Hole ; Then, A Round Image Of The ...
Starch
Starch. Ci2 H10 010=12 Atoms Of Carbon And 10 Of Water. This Substanc,e Occurs Abundantly In Vegetables, And Is Generally Obtained By Steeping The Powdered Grain Or Seed, Or The Raspings Of The Root, Bulb, Or Stem In Cold Water, Which Becomes Whit,e And Turbid, Mad, After Being Strained, Deposits ...
Stereoscope
Stereoscope. (gr. Erepeoc Solid, Crow*, I See) This Is An Instrument For Exhibiting Two Plane Perspective Views Of An Object, Taken From Different Stations, As One Having The Appearance Of Solidity. It Is The Invention Of Professor Wheatstone, And Was First Made Public And The Theory Of It Explained By ...
Sulphur Toning
Sulphur Toning. When An Arp,entine Photograph Having The Reddish Tint Produced By The Combination Of Suboxide Of Silver With Organic Matter Is Placed In Water Containing A Small Quantity Of Sul Phide Of Ammonium, The Tint Gradually Changes From Red To Purple, And Thence To Green-yellow. This Is Called Sulphur ...
Sulphuric Acid Oil Of
Sulphuric Acid. Oil Of Vitriol. Or When Hydrated, Ho, This Important Article Of Manufacture, Of Which Nearly A Hundred Thousand Tons Are Made Annually In Great Britain, Is In General Pro Duced By Burning Together In A Furnace A Mixture Of Sulphur And Nitre, The Proportions Varying From The One-eighth ...
Taiipenots Process
Taiipenot's Process. This Is A Dry Preservative Process In Which A Glass Plate Is First Collodionized And Excited, Then Coated With Iodized Albumen, And Excited A Second Time. Three Years Ago, Before The Problem Of Dry Collodion Was Solved, This Process, Disco Vered By Dr. Taupenot, Professor Of Chemistry At ...
Tent
Tent. When Views Are Taken By The Wet Collodion Process, In C C Which The Free Nitrate Of Silver Is Not Removed From The Plate By Washing, It Becomes Necessary To Operate Either In A Dark Room, Or Van, Or Tent, At Or Near The Spot Whence The View Is ...
The Grinding And Polishing
The Grinding And Polishing Op Lenses. The Piece Of Glass Of Which A Lens Is To Be Made Is Cut Out Of A Plate Of Sufficient Thickness, And This Is Brought Roughly Into Shape By Means Of Pincers, A Grind-stone, And Art Old Mould. A Pair Of Guages And Moulds ...
The Orthoscopic Lens
The Orthoscopic Lens. - The Term " Orthoscopic " Is Derived From The Greek Words Opfloc Right, And (fico7rew I See. The Meaning Is That The Lens Gives Images More Free From Distortion Than Other Lenses. The Orthoscopic Lens Is An Arrangement Consisting Of Two Achromatic Compound Lenses Separated By ...
Toom
Toom. In This State The Paper Is Bibulous, Or Blotting-paper, And The Next Operation Is To Size It. English Papers Are In General Sized With A Mixture Of Gelatine And Alum, To Which Sometimes Flour, Resin, And Yellow Soap Are Added. French Papers Are Sized With A Less Soluble Size, ...
Tracing Paper
Tracing-paper. There Are Two Kinds Of Tracing Paper, Viz., Transparent, And Black. Transparent Tracing-paper Is Made By Smearing The Paper With Boiled Oil,. Or Magilp, Or Colourless Dam Mar Resin Dissolved In Turpentine Or Benzole ; Or Better Still, With Canada Balsam Diluted With Turpentine. Black Tracing-paper Is Made By ...
Uranium Printing Process
Uranium-printing Process. A Sheet Of Paper Is Ftrst Rendered Sensitive To Light By Immersing It In A Strong Solution Of A Salt Of The Peroxide Of Uranium, (the Nitrate Is Probably The Best). It Is Then Dried, And Exposed Under A Negative To Clirect Light For About The Same Time ...
Varnishes
Varnishes. An Excellent Practical Account Of The Manufacture Of Varnishes, By Mr. J. W. Neil, Will Be Found In The 49th Volume Of The Transactions Of The Society Of Arts. But The Photographer Is Not So Much Concerned With Knowing The Particulars Of This Manu Facture In Its Various Branches, ...
Vinegar
Vinegar. See "acetic Acid." Visron. (latin, Videre To See.) The Phenomena Of Human Vision Voill Be Described Under Two Heads, Viz. Monocular Vision, And Binocular Vision. Monocular Vision. Vision Is Said To Be " Monocular" When Only One Eye Is Employed. The Human Eye May Be Considered As A Sort ...
Washing Prints
" Washing Prints. The Following Mode Of Washing Prints Appears To Be The Best That Has Yet Been Devised. The Acootmt Of It Was Given By The Author In Photographic Notes, No. 21. " After A Print Has Been Fixed In Hypo It Is Of The Utmost Impor Tance To ...
Water H09
Water. H0=9. Water May Be Considered As The Protoxide Of Hydrogen, Being Composed Of One Atom Of Oxygen And One Of Hydrogen ; Or, Which Is The Same Thing, Of Two Volumes Of Hydrogen And One Of Oxygen. Water In Its Ordinary State Exists Either As Rain, Or River, Or ...
Or Common View Lens
The Achromatized Meniscus, Or Common View Lens. This Lens Is Composed Of Two, Which Are Cemented Together With Canada Balsam. The First Is Of Flint Glass, And Double Concave ; The Second Of Crown Glass And Double Convex. The Concavity Of The Front Surface Of The Flint Lens Is Very ...