increases sensitiveness of Collodion plate,92;dissolves Iodide of Silver,86;discoloured by Albumen,245,329;forms a compound with Honey,289;with various other organic bodies,21;very little acted on by Glycerine,342;mode of recovering the Silver from,372.Nitrate Bath, mode of preparing for glass Positives,110,203;for Collodion Negatives,116,211;its power of dissolving Iodide of Silver, its occasional acidity and alkalinity explained,86;the mode in which Acetate of Silver may be formed in it,89;a list of the substances by which it is decomposed,90;changes by use,91;effect of these changes on sensitiveness,97;on intensity,102;care required to prevent it from yielding foggy pictures,104;a caution against the too frequent addition of alkali,204;quantitative testing of the Bath,371.Nitrite of Silver, adds to rapidity of development,102;tends slightly to produce fogging,104;solarizes the high lights,111.Nitric Acid, its preparation and properties,355;its oxidizing powers,12;impairs sensitiveness of Collodion film,93;lessens rapidity of development,98;tends to prevent fogging,104;sometimes usefully employed for glass Positives,110;contra-indicated for Negatives,116;its accumulation in the Nitrate Bath explained,94;mode of removing it,90;cannot exist in contact with Acetate of Silver,116;produces stains on cloth,215;mode of determining the strength of Commercial Nitric Acid,186;table of strength of Nitric Acid of different densities,378.Nitro-Sulphuric Acid, explained,77;process for making by mixed acids,186;by Oil of Vitriol and Nitre,190;should not be used cold,83.Nomenclature, chemical,315.Norris, Dr., his dry Collodion process,298.Notation, chemical,318.Organic bodies, chemistry of,324.Oxide of Silver, preparation and properties,17;dissolves in the Nitrate Bath, rendering it alkaline,88;properties of its solution in Ammonia,362;preparation of ditto,247;its solution in Nitrate of Ammonia used in Photography,249.Oxymel, keeping process,291;preparation of Oxymel,360.Paper, Photographic, selection of,240;peculiarity of English papers,241.Paper, sensitive, for printing.SeeSensitive Paper.Perchloride of Iron, preparation of toning Bath with,160.Permanence of Positives, mode of testing,169.Photographic image, chemical composition of,140;action of destructive tests on,145.Photographic properties of Salts of Silver,18;of Iodide of Silver upon Collodion,74.Photographic researches by the Author,140.Photography, historical sketch of,6;the term explained,61.Portrait lenses, theory of their construction,59;rules for their use,227;mode of finding chemical focus,229.Portraits, drapery for,66;directions for taking,220;the position of the Camera, and other points of importance,228;the time of exposure,221.Positive printing, on Albuminized paper, formulæ for,241;on plain paper, formulæ for,245;on Ammonio-Nitrate paper, formula for,246,258;by development, formulæ for,259;manipulatory details of printing, fixing, toning, washing, andmounting,251;process of toning by Sel d'or, theory of,134;practice of,267;reasons for the want of correspondence between different formulæ,257;use of Chloride of Gold in toning,132,271;theory of the preparation of the sensitive paper for Positives,122;theory of the process of fixing,129;of toning by Gold,132;the Author's researches,140;rationale of the printing process,120;composition of the image,140;fading of Positive prints,160;destructive action of Sulphur on,145;of oxidizing agents on,148;of Chlorine, acids, boiling water, etc., on,151;of combustion of coal-gas on,153;effect of damp air on,153;theory of mode of washing Positives,162;comparative permanency of prints,166;mode of testing permanency,169.Positives, definition of,106;Collodion Positives, theory of production of,108;formulæ for solutions for,201;development of,111,221;Collodion and Nitrate Bath best adapted for,109;mode of whitening by Bichloride of Mercury,112;solution for whitening,207;mode of backing up,226;spots and markings on,284;mode of printing Positives on Collodion,272.Positives, enlarged, mode of printing,272.Practice of Collodion process,183.Preservative processes for Collodion plates,289.Printing, Photographic, theory of,120;practical details of,240.Prism, refraction of light by,51;diagram of formation of spectrum by,47;explained,54.Prismatic spectrum,47,61.Protonitrate of Iron, preparation of,206;a feeble developer when free from excess of Sulphate of Iron,98;theory of its mode of action, and rules for its use,112;cannot be prepared in quantity by adding Nitrate of Potash to Sulphateof Iron,314;sometimes requires the addition of Nitrate of Silver,206.Protosulphate of Iron, its preparation and properties,29;its characteristics as a developer for Collodion Positives,111;not well adapted for developing Collodion Negatives,117;preparation of the solution for Positives,205;mode of applying it to the plate,221;to remove iron stains on glass,215.Pyrogallic Acid, its preparation and properties,28;solution for developing glass Positives,205;for Negatives,211;cannot be used without Acetic Acid,105;less adapted for developing paper pictures,178;requires addition of Nitric Acid when used for Positives,111;superior to Sulphate of Iron for developing Negatives,117,144;mode of obviating the brown discoloration of developing solutions,212.Pyroxyline, its nature and properties,75;preparation of, by Mr. Hadow's formula,186;by a rule-of-thumb mixture of the acids,188;by the Oil of Vitriol and Nitre process,190;details of immersing, washing, and drying,191;the glutinous variety produced by cold acids,83;recapitulation of the effects of varying the strength of the acidmixture,193;spontaneous decomposition of Pyroxyline,166.Reduction of metallic oxides by developers, theory of,26;of Silver salts by developers, theory of,30;practical details of reducing Silver compounds to metallic state,372.Salts nature of,310.Salts of Silver, their preparation and properties,12;their Photographic action,18;theory of their reduction by developer,30;directions for obtaining metal from,372.Sel d'or, toning process by, its theory,134;its practical details,267;its advantages,271;gives permanent prints,167.Sensitiveness, term explained,92;conditions favourable to,97.Sensitiveness of Collodion film, causes influencing,92;superior sensitiveness partially explained,74;preservation of sensitive film,288.Sensitive paper, theory of preparation of,22,122;its darkening by light described,123;preparation of Albuminized paper,241;of plain paper,245;of Ammonio-Nitrate paper,246,258;of paper for Negative processes,259;causes which affect the sensitiveness of Positive paper,123;which alter the colour of the image,126;spots and markings on,285;a large excess of Nitrate of Silver essential,124;the paper should not be kept too long,130,286.Serum of Milk, preparation of,262,355;used in Negative printing process,262.Shadbolt, Mr., his Honey keeping process,289;employs artificial light in Micro-Photography,237.Silver, properties of,362;estimation of, in Nitrate Baths,371;recovery from waste solutions,372;reduction from Chloride,374;stains, removal of,377.Size, mode of removing, from paper Positives,255.Solar spectrum,47,61.Soluble paper.SeePyroxyline.Specific gravity of liquids, mode of finding,375.Spherical aberration,56.Spirits of Wine, preparation and properties,330;not always sufficiently strong for Collodion,84;mode of rectifying,196;sometimes contaminated with, fusel oil,96.Spots on Collodion plates,279;on paper Positives,285;on prints obtained by development,266;on preserved Collodion plates,293.Stains, Silver, removal of,377.Stereoscope, invention of,67;theory of,68;Wheatstone's,69;Brewster's,70.Stereoscopic Photographs, rules for taking,71;practical details of,232.Stops, theory of use of,57;simple mode of making,228;position of the stop often important,230.Strength of acids, tables of,378.Subchloride of Silver, its preparation and properties,15;decomposed by fixing agents,141.Suboxide of Silver, its properties,18;forms compounds with organic matters. Citric Acid, Albumen, etc.,21.Substitution, laws of, explained,78.Sulphate of Iron.SeeProtosulphate of Iron.Sulphate of Quinine, absorption of chemical rays by,65.Sulphuric Acid, table of strength of,378.Sutton, Mr., theory of Sel d'or toning process,134;practical details of,267;Negative printing process,262;preparation of Serum of Milk for,355.Symbols, use of,318.Syruped Collodion film,289.Talbot, Mr., his discoveries,9;theory of Calotype process,176.Taupenot, M., his Collodio-Albumen process,181;practical details of,294.Temperature, its effect upon development of Collodion film,102;upon fogging,105;upon keeping Collodion,210;upon action of fixing Bath for paper Positives,130;upon Hypo toning Bath,136.Test-papers, use of,376.Toning Bath for Positives, with Sel d'or,134,267;with Hyposulphite and Gold,seeFixing and Toning Bath;with Chloride of Iron and Hyposulphite,160.Toning of Positives, term defined,121;may injure the stability of the proof,154;points to be kept in view to avoid fading,167;manipulatory details of,253;by Sel d'or,267.Transparencies, mode of printing,273.Varnishes for Collodion Photographs,226.View Lenses, directions for using,230.Vocabulary of Photographic chemicals,327.Washing Positive prints, rules for,162;details of,255.Waxed paper process, theory of,178.Weights and Measures, table of,379.