A Manual of Photographic Chemistry: Including the Practice of the Collodion Process |
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Common terms and phrases
Acetic Acid Albumen Alcohol alkaline Ammonia Ammonium appears Atomic weight becomes bottle Bromide Cadmium Camera chemical Chloride of Gold Chloride of Silver Collodion process colour compound containing Cotton crystals decomposed decomposition deposit developer dilute dissolved drachm effect employed Ether excess exposure film fixing bath fluid ounce formula free Nitrate Gallic Acid Gelatine glass Glycyrrhizine grains hence Hydrogen Hyposulphite of Soda intensity Iodide of Cadmium Iodide of Potassium Iodide of Silver Iodine iodized Collodion Lens Lenses liquid minutes Negative neutral Nitrate Bath Nitrate of Silver Nitric Acid Nitro-Sulphuric Acid obtained Oil of Vitriol organic matter Oxide Oxygen paper Photographic picture plain Collodion plate portion Positive Potash precipitate prepared present produce properties pure Pyrogallic Acid Pyroxyline quantity rays reducing agent removed sensitive shadows Sodium solution of Nitrate Stereoscopic substance Sulphate of Iron Sulphuric Acid surface temperature tint tion toning washing whilst yellow
Popular passages
Page 184 - ... combined with the tincture of the perchloride of iron was given, quinine being occasionally substituted for the chlorate during the period of convalescence. Many children, however, could be induced to take no medicine at all, especially among the poor. During the same period I was in the habit of applying a solution of nitrate of silver, of the strength of twenty grains to an ounce of water, to the fauces and palate with a...
Page 84 - In exemplifying further the importance of distinguishing between visual and actinic rays of light, we may observe, that, if the two were in all respects the same, photography must cease to exist as an art. It would be impossible to make use of the more sensitive chemical preparations, from the difficulties which would attend the previous preparation and subsequent development of the plates. These operations are now conducted in what is termed a dark room ; but it is dark only in a photographic sense,...
Page 379 - ... tightly compressed by replacing and bolting down the shutter. The amount of pressure required is not very considerable, but if the springs of the frame become too weak after a time, a few pieces of millboard may be placed beneath them. This operation may be conducted in the dark room ; but unless the light is very strong, such a precaution will be needless. The time of exposure to light varies much with the density of the negative and the power of the actinic rays, as influenced by the season...
Page 479 - Barium is a metallic element very closely allied to Calcium, the elementary basis of Lime. The Chloride of Barium is commonly employed as a test for Sulphuric Acid, with which it forms an insoluble precipitate of Sulphate of Baryta. It also slightly alters the colour of the Photographic image when used in preparing Positive paper, which may be due, in some measure, to a chemical combination of Baryta with Albumen...
Page 381 - On the other hand, if the general aspect of the print is a rich chocolate-brown in the case of Albumen, a dark slate-blue with Ammonio-Nitrate paper, or a reddish purple with paper prepared with Chloride and Citrate of Silver, the subsequent parts of the process will probably proceed well. If, in the exposure to ordinary diffused daylight, the shadows of the proof became very decidedly coppery before the lights are sufficiently printed, the Negative is in fault. Ammonio-nitrate paper highly salted...
Page 306 - Or a email thinlipped phial may be used. Appearance of the Negative image developed with Pyrogallic Acid, as a guide to the exposure to Light. — An under-exposed plate develops slowly. By continuing the action of the Pyrogallic Acid the high lights become very black, but the shadows are usually defective, nothing but the yellow Iodide being seen on those portions of the plate. After treatment with the Hyposulphite, the picture shows well as a Positive, but by transmitted light all the minor details...
Page 379 - THE NEGATIVE. The Exposure to Light. — For this purpose reversingframes are sold, which admit of being opened at the back, in order to examine the progress of the darkening by light, without producing any disturbance of position. The shutter at the back is removed, and the Negative laid flat upon the glass, Collodion side uppermost. A sheet of sensitive paper is then placed upon the Negative, sensitive side downwards ; next comes a layer of thick felt ; and the whole is then tightly compressed...
Page 515 - This salt, also termed Nitre, or Saltpetre, is an abundant natural product, found efflorescent upon the soil in certain parts of the East Indies. It is also produced artificially in what are called Nitrebeds. There are different qualities of Nitre sold in commerce, some of which contain much Chloride of Potassium, detected on dissolving the Nitre in distilled water, and adding a drop or two of solution of Nitrate of Silver. This impurity is injurious when the Nitre is employed for Photographic use...
Page 12 - ... zero in a state of perfect rest. In order to understand this, it must be borne in mind that the two opposite poles are very close together, and that they act simultaneously upon a system already very distant and almost completely astatic. It might be feared that the electro-magnet, without action on the needle at zero, acted on the needle already displaced by the action of the calorific radiation.