A Manual Of Photography

CHAPTER I. GENERAL REMARKS ON THE SOLAR AGENCY PRODUCING CHEMICAL CHANGE. The use of paper as the material upon which the coating that is to undergo a chemical change by exposure to solar radiations should be spread, claims our earliest attention on several accounts. Wedgwood and Davy employed paper and white leather in their earliest experiments ; and Mr. Talbot’s results, obtained also on paper, claim priority, as far as publication is concerned, over any other photographic process. Tor a long time the employment of paper was confined to our own country, our continental neighbours devoting their inquiries to the pro- cesses and physical phenomena connected with the use of the metallic plates constituting the tablets employed by Daguerre; but now they use the paper and glass processes in preference. Notwithstanding the statements which have been too often re- peated, to the effect that the practice of photography is exceed- ingly easy, that the manipulatory details of preparation present no difficulties, and that little more is necessary than to place a paper in a camera obscura, obtain a picture, and take it out