142 ANNUAL OF SCIENTIFIC DISCOVERY. 



S. D. Humphrey, of Canandaigua, N. Y., with a half-size American 

 camera, on a medium plate. The first picture was obtained by an ex- 

 posure of two minutes, the camera remaining permanent. During- this 

 short interval, the earth had moved forward so rapidly, that the figure 

 of the satellite was elongated to form an oval, or egg-shape picture. 

 The same peculiarity was also noticed in the pictures obtained by an 

 exposure for one minute, and also for thirty seconds, though in a 

 less degree. In these pictures, the configurations upon the moon's 

 surface were not delineated, but in the fourth picture, obtained by an 

 exposure of three seconds, the representation was strikingly clear and 

 distinct. The figure was round, and the representation of the surface 

 so perfect, that its appearance, when examined under the microscope, 

 somewhat resembled the full moon seen through a telescope. The 

 fifth picture was obtained by an exposure of only half a second, and 

 was little more than a shadow. The powerful agency and presence 

 of the chemical principle was sufficiently indicated by it. These sev- 

 eral pictures were all taken upon one occasion, on the night of the 1st 

 of September, a few hours before full moon. They conclusively show 

 that lunar light possesses the chemical principle or force, in a high 

 degree, and it is to this source that we may reasonably attribute its 

 supposed action in producing phosphorescence and other changes ia 

 animal or vegetable substances. Editors. 



PICTURES ON GLASS. 



AT a late meeting of the French Academy M. Evrard communi- 

 cated the details of a process he has discovered, by which pictures 

 can be taken upon glass. The principle of the discovery is a matrix 

 of albumen, rendered sensitive to the action of light by aceto-nitrate 

 of silver, and spread in a thin layer upon a plate of glass. The pro- 

 cess is to take a certain number of the whites of eggs, and remove all 

 the non-transparent part, and then add a few drop.s of a saturated so- 

 lution of iodate of potassium, then beat the eggs into a froth, and allow 

 the whole to settle. The plate of glass must be well cleaned with 

 alcohol, and the albumen is then spread over it, in a thin layer, with 

 another piece of glass. It is important that the glass should have a 

 perfect, thin coat adhering to it, and to obtain this it must next be 

 hung up by one of the corners, so that the excess may drain off, after 

 which it should be placed to dry upon a level board, and screened 

 from the dust. Then the glass is dipped into a solution of aceto- 

 nitrate of silver, face downwards, after which it is stirred about in a 

 basin of clean water for a few seconds, and is then completely sensi- 

 tive to receive photographic impressions, either when it is moist or 

 dry. It is then placed ia the camera-obscura, after which it is dipped 

 for a short time into a bath of gallic acid, in which there is a little of 

 the nitrate of silver. Finally, it is washed in water, and having been 

 immersed in a solution of bromide of potassium, it is again washed, and 

 left to dry in a horizontal position in a dark room. 



