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. * * * * * Just published, price 1s., free by Post 1s. 4d., THE WAXED-PAPER PHOTOGRAPHIC PROCESS of GUSTAVE LE GRAY. New Edition. Translated from the last Edition of the French. GEORGE KNIGHT & SONS., Foster Lane, London, Manufacturers of Photographic Apparatus and Materials, consisting of Cameras, Stands, Coating Boxes, Pressure Frames, Glass and Porcelain Dishes. &c., and pure Photographic Chemicals, suited for practising the Daguerreotype, Talbotype, Waxed-Paper, Albumen and Collodion Processes, adapted to stand any Climate, and fitted for the Requirements of the Tourist or Professional Artist. Sole Agents in the United Kingdom for VOIGHTLANDER & SON'S celebrated Lenses for Portraits and Views. General Depôt for Turner's, Whatman's, Canson Frères', La Croix, and other Talbotype Papers. Instructions and Specimens in every Branch of the Art. * * * * * 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. * * * * * TO PHOTOGRAPHERS.--MR. PHILIP DELAMOTTE begs to announce that he has now made arrangements for printing Calotypes in large or small quantities either from Paper or Glass Negatives. Gentlemen who are desirous of having good impressions of their works, may see specimens of Mr. Delamotte's Printing at his own residence, 38. Chepstow Place, Bayswater, or at MR. GEORGE BELL'S, 186. Fleet Street. * * * * *