A Manual Of Photography

44 HISTORY OF PHOTOGRAPHY. The same plate may be employed for many successive trials provided the silver be not polished through’to the copper It is very important, after each trial, that the mercury be removed be » Ï S Ï polishing with pumice-powder and oil. If this be neglected, the mercury finally adheres to the silver and sood drawings cannot be obtained if this amalgam is present b Section II. — Improvements in Daguerreotype. It was announced that the inventor of the daguerreotype had extent^s to1 sensibility of his plates to such an production of ^stantaneous exposure sufficient for the ,.th ^«t eflects ; consequently, securing faithful pressions of moving objects. In a communication with which I was favoured from M. Daguerre, he said,-" Though the to nublishit ^.^w discovery i« certain, I am determined not to publish it before I have succeeded in making the execution of it as easy to every body as it is to myself. I have annoyed immediately at the Loyal Academy of Paris, merely to take By means ofSth fain my risht to ^^priority of the invention. / v UC" Process, it shall be possible to fix the Jp Greets in motion, such as public ceremonies market places covered with people, cattle, |c.—the effect being instan taneous. J mstan- In 1844, M. Daguerre, in a letter to M. Arago, published this process; but it proved so complex in its manipulatory details and so very uncertain, that it has not been adopted. As it is’ however curious, and involves the use of some agents not ordinarily employed, it is thought advisable to include it within this volume. We quote from the Comptes A •i 1844. wumpLcs Etendus for April thit T°h. ^"^been kind enough to announce to the Academy YcLA ^Apy senes of experiments, at recognising in *““ â^àt in the present state of my process, the byer sensible to light being too thin, could not furnish all the gradation of tints necessary for reproducing nature with relief oniness; indeed, although the proofs hitherto obtained ™."'licient in purity, they leave, with a few exceptions relief.1_desired with relation to general effect and out °very fin^ by means of the layer of water, as T have pointed h „Pressions are very rapidly obtained, but which are aim wanting in relief, on account of the thinness of the sensible layel