PHOTOGRAPHY.--Collodion (Iodized with the Ammonio-Iodide of Silver).--J. B. HOCKIN & CO., Chemists, 289. Strand, were the first in England who published the application of this agent (see _Athenæum_, Aug. 14th). Their Collodion (price 9d. per oz.) retains its extraordinary sensitiveness, tenacity, and colour unimpaired for months: it may be exported to any climate, and the Iodizing Compound mixed as required. J. B. HOCKIN & CO. manufacture PURE CHEMICALS and all APPARATUS with the latest Improvements adapted for all the Photographic and Daguerreotype processes. Cameras for Developing in the open Country. GLASS BATHS adapted to any Camera. Lenses from the best Makers. Waxed and Iodized Papers, &c. * * * * * PHOTOGRAPHY.--XYLO-IODIDE OF SILVER, prepared solely by R. W. THOMAS, has now obtained an European fame; it supersedes the use of all other preparations of Collodion. Witness the subjoined Testimonial. "122. Regent Street "Dear Sir,--In answer to your inquiry of this morning, I have no hesitation in saying that your preparation of Collodion is incomparably better and more sensitive than all the advertised Collodio-Iodides, which, for my professional purposes, are quite useless when compared to yours. "I remain, dear Sir, "Yours faithfully, "N. HENNEMAN. Aug. 30. 1852. to Mr. R.W. Thomas." MR. R. W. THOMAS begs most earnestly to caution photographers against purchasing impure chemicals, which are now too frequently sold at very low prices. It is to this cause nearly always that their labours are unattended with success. Chemicals of absolute purity, especially prepared for this art, may be obtained from R. W. THOMAS, Chemist and Professor of Photography, 10. Pall Mall. N.B.--The name of Mr. T.'s preparation, Xylo-Iodide of Silver, is made use of by unprincipled persons. To prevent imposition each bottle is stamped with a red label bearing the maker's signature. * * * * * KERR & STRANG, Perfumers and Wig-Makers, 124. Leadenhall Street, London, respectfully inform the Nobility and Public that they have invented and brought to the greatest perfection the following leading articles, besides numerous others:--Their Ventilating Natural Curl; Ladies and Gentlemen's PERUKES, either Crops or Full Dress, with Partings and Crowns so natural as to defy detection, and with or without their improved Metallic Springs; Ventilating Fronts, Bandeaux, Borders, Nattes, Bands à la Reine, &c.; also their instantaneous Liquid Hair Dye, the only dye that really answers for all colours, and never fades nor acquires that unnatural red or purple tint common to all other dyes; it is permanent, free of any smell, and perfectly harmless. Any lady or gentleman, sceptical of its effects in dyeing any shade of colour, can have it applied, free of any charge, at KERR & STRANG'S, 124. Leadenhall Street.