PHOTOGRAPHIC APPARATUS, MATERIALS, and PURE CHEMICAL PREPARATIONS. KNIGHT & SONS' Illustrated Catalogue, containing Description and Price of the best forms of Cameras and other Apparatus. Voightlander and Son's Lenses for Portraits and Views, together with the various Materials, and pure Chemical Preparations required in practising the Photographic Art. Forwarded free on receipt of Six Postage Stamps. Instructions given in every branch of the Art. An extensive Collection of Stereoscopic and other Photographic Specimens. GEORGE KNIGHT & SONS, Foster Lane, London. * * * * * IMPROVEMENT IN COLLODION.--J. B. HOCKIN & CO., Chemists, 289. Strand, have, by an improved mode of Iodizing, succeeded in producing a Collodion equal, they may say superior, in sensitiveness and density of Negative, to any other hitherto published; without diminishing the keeping properties and appreciation of half tint for which their manufacture has been esteemed. Apparatus, pure Chemicals, and all the requirements for the practice of Photography. Instruction in the Art. THE COLLODION AND POSITIVE PAPER PROCESS. By J. B. HOCKIN. Price 1s., per Post, 1s. 2d. * * * * * PHOTOGRAPHY.--HORNE & CO.'S Iodized Collodion, for obtaining Instantaneous Views, and Portraits in from three to thirty seconds, according to light. Portraits obtained by the above, for delicacy of detail rival the choicest Daguerreotypes, specimens of which may be seen at their Establishment. Also every description of Apparatus, Chemicals, &c. &c. used in this beautiful Art.--123. and 121. Newgate Street. * * * * * PHOTOGRAPHIC CAMERAS.--OTTEWILL'S REGISTERED DOUBLE-BODIED FOLDING CAMERA, is superior to every other form of Camera, for the Photographic Tourist, from its capability of Elongation or Contraction to any Focal Adjustment, its Portability, and its adaptation for taking either Views or Portraits.--The Trade supplied. Every Description of Camera, or Slides, Tripod Stands, Printing Frames, &c., may be obtained at his MANUFACTORY, Charlotte Terrace, Barnsbury Road, Islington. New Inventions, Models, &c., made to order or from Drawings. * * * * * PHOTOGRAPHY. A COMPLETE SET OF APPARATUS for 4l. 4s., containing an Expanding Camera, with warranted Double Achromatic Adjusting Lenses, a Portable Stand, Pressure Frame, Levelling Stand, and Baths, complete. PORTRAIT LENSES of double Achromatic combination, from 1l. 12s. 6d_._ LANDSCAPE LENSES, with Rack Adjustment, from 25s. A GUIDE to the Practice of this interesting Art, 1s., by post free, 1s. 6d. French Polished MAHOGANY STEREOSCOPES, from 10s. 6d. A large assortment of STEREOSCOPIC PICTURES for the same in Daguerreotype, Calotype, or Albumen, at equally low prices. ACHROMATIC MICROSCOPES. Beautifully finished ACHROMATIC MICROSCOPE, with all the latest improvements and apparatus, complete from 3l. 15s., at