Miscellaneous Intelligence. 141 



two added together, make C 24 H 17 17 +5N0 5 , Pelouze's formula, for 

 pyroxyline.* With cane sugar, glucose, mannite, sugar of milk, dex- 

 trine, and gum, analogous fulminating compounds have been formed by 

 these chemists. They have succeeded in crystallizing the nitric man- 

 nite, and obtained for it the formula C 12 7 H 7 +5N0 5 . 



6. Process for Photographs upon paper ; by M. Blanquaht-Evrard, 

 (Comptes Rendus, Jan., 1847.) — This process is in part a modification 

 of the Calotype, and is, according to its author, susceptible of many 

 variations. The principles upon which it depends, are, 1st, the thorough 

 impregnation of the paper by the photographic agent, so that the image 

 is formed within the paper ; and 2d, the perfection of surface given to a 

 moist paper by placing it upon a glass, which, in the camera, is turned 

 toward the lens, the image being formed on the wet surface of paper 

 in contact with the glass. 



As this process seems to be more simple than any other, and within 

 the reach of persons of moderate skill, we give it somewhat in detail. 

 For the first or negative proof, the very best letter paper is to be taken ; 

 its texture should be close and uniform ; the surface very smooth. 

 This paper is to be floated on the surface of a solution of one part 

 nitrate of silver in thirty parts distilled water, observing the usual pre- 

 cautions of not including air bubbles, &c. After one minute the paper 

 ,s amoved, held up to drain by a corner, and then laid upon some im- 

 permeable surface and allowed to dry slowly. 



Another solution is prepared of 25 parts iodid of potassium, 1 part 

 hromid of potassium, and 560 parts distilled water. In this solution 

 the paper is entirely immersed, with the silver side up, and suffered to 

 remain from one and a half to two minutes, according to the tempera- 

 te; it is then carefully withdrawn, holding it by two corners, and 

 P'aced in a large vessel" full of pure water ; it is next hung up to dry 

 u pon a string, being fastened by one corner. 



. Paper thus prepared should be protected from the light and preserved 

 jn a pasteboard case, but not packed too closely. It will keep for months. 

 I he solutions kept in vessels covered by opaque paper may be used to 



exhaustion. 



To take a proof, a smooth glass is made quite level upon a suitable 

 su PPort, and upon it are poured a few drops of a solution of 6 parts 

 !m «"e of silver, 1 1 parts crystallizable acetic acid, and 64 parts distilled 

 J*ter; (half of the water should be taken to dissolve the nitrate, and 

 lh * remainder added about an hour after the acid has been mixed with 



l«e first 



portion.) 



.The paper is next to be applied to this liquid on the glass, the nitrated 

 s, <*e downwards, and smoothed by the hand until there is a perfect con- 

 «« with the glass without any folds or bubbles. One or more pieces 

 J ™>** paper, according to the thickness, are then to be p'^ed upoa 

 ,hls ; next a second glass of the same size, and the whole bemg ; properly 

 sec "red, is used in the camera as a daguerreotype plate I he tir ne of 

 ^posure varies according to the temperature, and is about one-touitn 



*at required for plates prepared with chlorid of iodine. 



" ,n ?* », P- 205, there is an error arising from ^gS^^ ^"^ ^ 

 »**>iine, the 6HO, which is separated in the process of formation. 



