NATURAL PHILOSOPHY. 145 



piece of blotting-paiier upon an apparently plain piece ot white 

 all)umenized paper, moistening tiie two, and producing at once a 

 photographic picture. The explanation of this is simple, and is 

 doubtless familiar to old photographic experimentalists ; we prac- 

 ticed the same feat a dozen years ago. It consists in bleaching, 

 until it is white and invisible, by means of bichloride of mercury, 

 a silver print; then, taking a piece of blotting-paper which has 

 been previously immersed in a solution of hyposulphite of soda, 

 and placing it in contact Avith the immersed print; this, when 

 moistened, at once darkens the bleached image, and a picture, 

 consisting chiefly of sulphide of mercuiy, is i^roduced. We have 

 received some examples from Mr. Swan, and details will be 

 found in Dr. VogePs (xcrman letter in this number. We have 

 just received from Mr. Hughes's establishment a still prettier 

 ajjplication of parlor magic, in which, by placing an apparently 

 blank piece of paper in a solution — the material for which is 

 inclosed in the packet — a beautiful blue print is produced. This 

 is doubtless the result of one of the applications of the Cj'anotype 

 process of Sir J. Herschell, which may be made to produce many 

 beautiful transformations. — Photographic News. 



The Magic Photograph is selling in Paris and London, in two 

 envelopes, one containing pieces of white albumenized paper; 

 the other, slips of white blotting-paper of a corresponding size. 

 One of the former is moistened with water, and a piece of jiaper 

 from the other envelope, likewise wetted, is laid thereon, when a 

 beautiful photograph is immediately developed on its albumenized 

 sui'face. Photograplis have, of course, been printed in the usual 

 manner on the albumenized slips, and then decolorized with 

 bromic or iodic acid, or some such agent; the other i^ieces of 

 pajjer have been soaked in hyi^osulphite of soda, and the appli- 

 cation of this reducing agent to the hidden photograph instantly 

 brings it again to view. 



SUBMARINE PHOTOGRAPHr. 



A French artist, M. Bazin, has been experimenting lately, with 

 the design of obtaining photographs of sunken vessels, so that, in 

 attempting to raise the same, positive knowledge can be had of 

 their relative positions. To accomplish this, M. Bazin descends 

 to the necessary depth, in a strong sheet-iron box, which he calls 

 his "photographic chamber." Thick glass windows afford every 

 facility for making the necessary preliminaiy observations, and 

 the picture is taken by the aid of a strong electrical light. 



An unpleasant feature of the apparatus is, that the oj^erator is 

 absolutely hermetically scaled, for no means are provided for sup- 

 plying air, the chamber being constructed of a proper size to con- 

 tain the quantity required during the ten or twelve minutes 

 occupied in obtaining a negative. 

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