Suche löschen...
The photographic news
- Bandzählung
- 6.1862
- Erscheinungsdatum
- 1862
- Sprache
- Englisch
- Signatur
- F 135
- Vorlage
- Hochschule für Grafik und Buchkunst Leipzig
- Digitalisat
- Hochschule für Grafik und Buchkunst Leipzig
- Digitalisat
- SLUB Dresden
- Lizenz-/Rechtehinweis
- Public Domain Mark 1.0
- URN
- urn:nbn:de:bsz:14-db-id1780948042-186200003
- PURL
- http://digital.slub-dresden.de/id1780948042-18620000
- OAI-Identifier
- oai:de:slub-dresden:db:id-1780948042-18620000
- Sammlungen
- Fotografie
- LDP: Historische Bestände der Hochschule für Grafik und Buchkunst Leipzig
- Bemerkung
- Seite 1-72 fehlen in der Vorlage. Vorlagebedingter Textverlust.
- Strukturtyp
- Band
- Parlamentsperiode
- -
- Wahlperiode
- -
- Bandzählung
- No. 204, August 1, 1862
- Digitalisat
- SLUB Dresden
- Strukturtyp
- Ausgabe
- Parlamentsperiode
- -
- Wahlperiode
- -
-
Zeitschrift
The photographic news
-
Band
Band 6.1862
-
- Ausgabe Ausgabe 73
- Ausgabe Ausgabe 85
- Ausgabe Ausgabe 97
- Ausgabe Ausgabe 109
- Ausgabe Ausgabe 121
- Ausgabe Ausgabe 133
- Ausgabe Ausgabe 145
- Ausgabe Ausgabe 157
- Ausgabe Ausgabe 169
- Ausgabe Ausgabe 181
- Ausgabe Ausgabe 193
- Ausgabe Ausgabe 205
- Ausgabe Ausgabe 217
- Ausgabe Ausgabe 229
- Ausgabe Ausgabe 241
- Ausgabe Ausgabe 253
- Ausgabe Ausgabe 265
- Ausgabe Ausgabe 277
- Ausgabe Ausgabe 289
- Ausgabe Ausgabe 301
- Ausgabe Ausgabe 313
- Ausgabe Ausgabe 325
- Ausgabe Ausgabe 337
- Ausgabe Ausgabe 349
- Ausgabe Ausgabe 361
- Ausgabe Ausgabe 373
- Ausgabe Ausgabe 385
- Ausgabe Ausgabe 397
- Ausgabe Ausgabe 409
- Ausgabe Ausgabe 421
- Ausgabe Ausgabe 433
- Ausgabe Ausgabe 445
- Ausgabe Ausgabe 457
- Ausgabe Ausgabe 469
- Ausgabe Ausgabe 481
- Ausgabe Ausgabe 493
- Ausgabe Ausgabe 505
- Ausgabe Ausgabe 517
- Ausgabe Ausgabe 529
- Ausgabe Ausgabe 541
- Ausgabe Ausgabe 553
- Ausgabe Ausgabe 565
- Ausgabe Ausgabe 577
- Ausgabe Ausgabe 589
- Ausgabe Ausgabe 601
- Ausgabe Ausgabe 613
- Register Index 619
-
Band
Band 6.1862
-
- Titel
- The photographic news
- Autor
- Links
- Downloads
- Einzelseite als Bild herunterladen (JPG)
-
Volltext Seite (XML)
362 THE PHOTOGRAPHIC NEWS. [August 1,1862. pyro and silver, as the tendency, once evinced, is very per sistent, and will probably occur again at once on attempting to intensify further. Perhaps the best remedy which can be applied, when once the evil is in existence, and cannot be removed by cyanide without endangering the picture, is to treat the plate with a dilute solution of bichloride of mercury, which will not affect, in any appreciable degree, the general image, but will convert the red deposit, which is very non-actinic, and a serious detriment in printing, into a thin one of bluish white, through which the light can easily pass, and will therefore render the defect of comparatively small impor tance in printing. Prevention is best; but when the time for prevention is past, this remedy will be found valuable. 4 PHOTOGRAPHIC CHEMICALS:' TuEr Manufacture, Adulteration, and Analysis. Potassium Salts.—Permanganate of Potash (continued).— Mr. Robert Hunt, to whom photography owes so much, has shown that the metallic acid contained in this salt is possessed of photographic properties ; for instance, if two bottles are filled with this solution, and one of them be placed in the sunshine, whilst the other is carefully preserved in darkness, it will be found that the solution exposed to the sun will very rapidly throw down a deep brown preci pitate, whereas the one in the dark remains for some time quite clear. This experiment, if cautiously made in weak diffused daylight, will exhibit the same change, although more slowly; showing in a very remarkable manner the influence of the solar rays in determining the tendency to precipitation. If a dilute solution of permanganate of potash is washed over paper, it imparts to it a brown colour, owing to the reduction of the acid by the organic matter, and pre cipitation of binoxide of manganese. The sun’s rays have a tendency to discharge this colour, and thus give a posi tive image. The addition of a small quantity of nitrate of silver to paper prepared with this salt of manganese renders it brown, and causes it to assume a very intense black colour upon exposure to light. Arseniate of Potash.—Arsenic and arsenious acids have frequently been employed in photography; and, indeed, some experimenters have succeeded in obtaining very excel lent photographic pictures by using the liquor arsenicalis of the pharmacopia. Mr. Hunt says that paper washed with this solution, and then with nitrate of silver, changes with tolerable readiness, and darkens to a perfectly jet black: the photographs resulting from this process are very decided in their contrasts of black and white. The salt may be formed by powdering together equal weights of arsenious acid and nitre, and throwing the mixture gradually into a red-hot crucible, the mass is then allowed to cool, when it is dis solved in water, the solution filtered and left to crystallize. It may also be formed by mixing carbonate of potash and arsenic acid together in proper proportion, and evaporating, the mono-salt crystallizes out. The crystals are permanent in the air, and taste somewhat like nitre; this experiment, however, is very dangerous, as the salt is terribly poisonous. It dissolves in about five parts of water, at the ordinary temperature, and in a much smaller quantity of hot water; it is insoluble in alcohol. The crystals are exactly similar in appearance and crystalline form as the monophosphate of potash. Arsenite of Potash.—This combination is not known in very definite form. Three salts are supposed to exist, but they are difficult to crystallize. Pasteur succeeded in obtain ing a compound in the crystalline form, by digesting arsenious acid in excess in a cold solution of potash ; upon adding alcohol to the resulting oily, alkaline, liquid, it became thick and turbid, and after a few days deposited beautiful crystals on the sides of the vessel, having the form of rectangular prisms. When nitrate of silver is added to this solution, the yellow neutral arsenite of silver is preci ¬ pitated, mixed with free arsenious acid, while the supematani liquid acquires an acid reaction. In some photograpio experiments it may be advisable to avoid this acidity. This may be effected by digesting the crystallized salt with exoes of potash, and precipitating with alcohol. In this manner s salt is formed which gives, with nitrate of silver, a yellow precipitate, containing no free arsenious acid, whilst die supernatant solution becomes neutral. Carbazotate of Potash.— Carbazotic acid is so frequently used as a test for potash, and is now becoming an article of such importance, that a short notice of this salt may not bo out of place here. Carbazotic acid is prepared by acting upon numerous complex organic substances with fuming nitric acid. At present it is made in enormous quan tities from some of the products of the distillation of coal, the hot solution obtained by acting upon this mixture with nitric acid must be decanted from the undissolved portion, when the carbazotic acid will be deposited as the liquid cools ; it may be purified by washing with cold water, and converting it into the potash salt. Carbazotate of potash forms orange yellow, needle-shaped crystals, freely soluble in boiling water, but requiring 260 parts of cold water for solution. By dissolving it in boiling water, and adding dilute nitric acid, it is decomposed, and crystals of car bazotic acid will be deposited as the liquid cools, nitrate of potash remaining in solution. This acid crystallizs in long pale yellow brilliant rectangular plates which an readily soluble in alcohol and ether. It requires between 80 and 90 parts of cold water for its solution, forming 8 liquid of a bright yellow colour, and stains the skin yellow. It has an intensely bitter taste, on which account it is re ported to be used by some persons as a fraudulent substitute for a portion of the hops in beer. The great use of carba zotic acid is, however, for dyeing purposes, as it communi- cates to silk and wool a brilliant yellow colour. Cloth dyed in this manner might be advantageously employed as an adjunct to the yellow glass in photographic labora tories. Silico-fluoride of Potassium.—Another useful test for potash is the hydro-fluo-silicic acid. This is formed by A rather difficult process, by the decomposition of fluoride ot silicium by water, or by dissolving silica in dilute hydro fluoric acid. When the acid is added to a soluble potasl salt silico-fluoride of potassium is thrown down ; the preci pitate forms in a very characteristic manner, at first it sepa rates very slowly and is scarcely visible, afterwards it P!® duces prismatic colours in the liquid, and is finally d posited as a transparent gelatinous iridescent mass, whid dries upon the filter to a soft white powder. It is vel sparingly soluble in water, but more freely so when W* water is hot. Sulpho-cyanide of Potassium.—This is rather an in portant salt, and is much used as a test for iron. It is P" pared on the large scale by mixing 46 parts of dried fert cyanide of potassium, 17 parts of carbonate of potash, A00 32 parts of sulphur, powdering them well together, A0S heating until the mixture attains a state of clear al tranquil fusion ; the heat is then raised to low redness tod compose the hyposulphite of potash; it is afterwards left 1° cool, boiled with alcohol, and filtered. On the filter the 1 remain bisulphide of iron and sulphate of potash, whils the transparent and colourless filtrate yields crystals of PaT sulpho-cyanide of potassium. This is a very advantagcot. process devised by Liebig, the product is yielded in lars, quantity and very pure. The salt forms long, transparet 1 colourless striated prisms and needles ; at a temperatua considerably below redness they fuse to a transparent “on colourless liquid, which solidifies to a crystalline mass cooling. It deliquesces in the air and dissolves abundart [ in water, producing a considerable degree of cold. It ;n wise dissolves in alcohol, especially when hot, it has as“Iike and cooling taste like nitre, and is a narcotic poison " hydrocyanic acid. When in aqueous solution it sU j gradual decomposition, even when kept in a well-stoPPS: Ave bottle, solutiot Kitr acting acid after a coloure cyanog dissolv heated and le: at first: potash, deposit rated b titro-pi latter b remain: nitro-pi lization He in i [or of s< itlphid (iately ng a oluble hany s fom a this im nere : irlmire Qapsf thant Jaller lorefe obtain "tent, fmplo This d iss the st Teferr Hr. G3rvin Photo Benlpt BI REPROL Photog lererth Promin Signor fie sp Rentler Elgin 1 Rprodt Are ma Poksess Hi Umer Breg Rutin Me ph Man Pet fev Mice
- Aktuelle Seite (TXT)
- METS Datei (XML)
- IIIF Manifest (JSON)