Early Work In Photography
A Text-book For Beginners

32 Early Work in Photography. Therefore it follows that if, after development, the plate be immersed in a solution of hypo, the creamy-looking chloride of silver will be dissolved, leaving the insoluble metallic image upon a transparent film of colourless gelatine. If the student will now examine the transparent positive tliat accompanies this handbook, he will understand exactly the qualities that must be sought when making lantern slides by development.... And now, to come to the matter of printing and developing in detail, we must impress one vital fact upon the student: The lantern plates are extremely sensitive to the faintest ray of white light, though they are not affected by deep yellow, orange, or red light. The best and most comfortable light to use while working witli lantern plates is a ricli yellow, such as is transmitted through a pane of yellow glass, covered witli one thickness of canary medium. It is positively necessary to use deep ruby light only when dealing with the plates of ultra sensitiveness, to be described in a later chapter. Let us now shut ourselves in the dark room, and prepaie to make a trial exposure : Place the negative (film up) on a sheet of glass in the printing frame; put a lantern plate (film down) upon it, and re-adjust the back of tlie frame. And here it may be well to tell tlie student that makers of lantern plates always pack their plates in a similar manner, i.e. film to film, witli either a slip of paper or small piece oi card between. When a box of plates is opened (of course, only by yellow light, as described) it will be observed that the first plate always has its back (or glass side) upwards. The next plate will have its film side upward, and the next one the glass side upward, and so on..: But, if at any time there be any doubt as to which is the film side (and they are so exactly similar that this may easily liappen in the yellow light of the dark room), the matter may be easily set right. Hold a plate by the edges, and turn itaJ such an angle towards the lantern that the light is reflected upon it ; tlien breathe lightly on the surface. If the film side be uppermost, the breatli will leave no impression, but, it the glass side be upwards, the breatli will condense upon it. This is the simplest and neatest method we know for deter- mining the film side of a plate. . ._ The negative and sensitive plate being in contact, and ready for exposure, it is necessary to completely cover tlie negative, except during the time of actual exposure. Inis may be done with a book, or a piece of cardboard. The frame and its contents must next be taken into daylight (the