WITH THE MICROSCOPE. 2// 



articles in the developer, or following its re-application, as honey, 

 raspberry syrup, &c., or the image when cleared by cyanide of 

 potassium or hyposulphite of soda and well washed, toned by a gold- 

 toning solution. 



If to be taken on a wet plate, a proper copying camera or two 

 draw cameras are commonly used : the negative, face towards the 

 interior of the camera, is placed in the ordinary camera slide, and 

 this inserted in its place and opened. A portrait combination is 

 fitted to the opposite end of this camera if the negative is to be in any 

 way enlarged, if not to another camera, and the front lens made to 

 face the negative ; the two cameras are then fixed face to face, and 

 the light around the aperture of the lenses and the junction with 

 the additional camera, made absolutely light-tight : the cameras thus 

 fixed to any board are placed so that the negative faces a north 

 light ; by means of the rack and pinion of the combination, and 

 the draw-part of either or both cameras, a sharp image of the 

 negative is to be formed on the greyed glass of the second camera, 

 and then received as in the ordinary manner on the prepared plate : 

 a short exposure only is needed. It is as well to limit the field by 

 placing a piece of thick black paper with the necessary size or 

 shaped aperture in it, on the back of the negative before placing it 

 in the slide ; care should be taken to secure the negative in its 

 position in case of accident. Or a copy can be made by placing 

 the negative in a vertical frame supported on a table near an 

 open window, and a large white card or mirror placed a little 

 distance, at an angle behind it, so as to illuminate the surface 

 equally by transmitted light, and the ordinary camera 'used as in 

 copying engravings or pictures, care being taken that the reflected 

 light from the screen is not thrown into the lens as well as 

 transmitted through the negative. A proper copying camera is 

 the best. In enlarging, some employ a special reflector, when the 

 position of the negative must be arranged with care. The positive 

 thus obtained can in its turn be made to furnish a second negative 

 of a similar, larger, or smaller size. 



As these photographs abound in delicate detail, an oxy-hydrogen 

 or electric lantern with achromatic lenses is necessary for their proper 

 display. The lantern and arrangements for producing the light 

 are shown in plate LV, fig. 341. The lantern should be made of 

 old seasoned mahogany, so that warping may not be produced by 

 the very intense heat of the lime light. Behind the spring stage, 

 which carries the photographic slide, M. T. T. Taylor has placed a 

 combination of lenses, 3^ inches in diameter, called "the con 

 denser." (See paper in Reports of the British Association ) The 



