The Optical Magic Lantern Journal (September 1897)

154 The Optical Magic Lantern Journal and Photographic Enlarger. placed on it nearly at the bottom of the grate, coke is lightly packed round and left to burn gently. When it becomes incandescent throughout, the mixture of residue and flux is introduced into the crucible a little at a time . to keep it from boiling over. When the pot is nearly full the lid is adjusted, the coke piled on, and the draught increased until the surface of the melted flux in the crucible looks quiet, and shows no signs of ebullition (from time to time an iron stirrer is used to expedite the separation of the reduced metal). The coke is now packed all over the crucible and cover, and the draught kept up, adding coke occasionally for an hour or so. It is then ‘tested by dipping an iron rod—the stirrer will do—into it, and examining the adhering mass. Ifthe process is completed, there will be noglobules of silver in it; but if not, it will be seen spangled throughout with globules of the metal, indicating that more heat must be applied, or a longer time given in the fire. When the silver has all gone down the fire is allowed to die, and the crucible cooled and broken with a hammer. The silver should now be seen as a bright button at the bottom, any flux adhering can be dissolved off with hot water. The sulphide residue is treated precisely similar in either case. If the metal seems too difficult fo separate, a little more borax added during the melting will expedite matters. These buttons of silver require refining. To do this the metal is put into a plumbago crucible and melted, and this requires more heat than in the first case. When fluid, the crucible is lifted out of the fire with the tongs, and poured from a height of four or five feet into a deep pan of clean cold water, from which it is removed in a granulated state, and dried. The principal difficulty with amateurs is getting a fire with sufficient heat, and it is a hopeless task without. Some close kitchen ranges I have seen could be made to give plenty of heat; an open fire will rarely do so. NEW ‘“‘INCANTO’’ ACETYLENE GAS GENERATOR. Improvements have been added to the “ Incanto generator,” by Messrs. Thorn & Hoddle, inasmuch as it is-possible now with this apparatus to get perfect light at once without the necessity of waiting until a certain quantity of diluted gas had been consumed or allowed to escape. There has | also been added a simple :and automatic device where any extra gas may be. allowed to escape after the holder is full. We have prepared a sectional sketch the better to explain the means by which this is ‘achieved. The tank into which the water is placed is represented as 4; B being the gas holder. To the upper part of B, and connected with the opening on top is a large tube or division c, and it is into this that the carbide holder p is placed. The connections between b, where the gas is generated, and B, where it is stored, are at the lower end of c, which is open, and also at the small connecting tube J, which is fitted witha tap. If p be charged and the tap 3 closed and c opened, it follows that no water can reach p when the holder is placed in the water, until 5 be opened, when immediately gas is generated and the holder rises from the water which previously filled it. Should the apparatus stand in disuse and more gas be evolved than it will contain, an outlet is formed at H as soon as the end of the cone rises from the water. The reason for cone-shaped outlet is to keep a free passage in the pipe. Rubber tubing is attached at 1 and conducted outside. The stand pipe is shown at E which communicates with the condenser r, which in turn is connected with the service pipe a. 10: oo eo * Editorial Mable. ¥¥ FAR TR RAR RRR RR RRR 6S ‘SHAKESPEAREAN GUIDE TO STRATFORD-ON-AVON.” London : Dawbarn and Ward, Ltd., 1s. net (cloth bound). This guide, which has been written by the joint editors of the Photogram, viz., H. Snowden Ward and Catherine Weed Ward, will be found to be a most useful handbook for those visiting the vicinity on which it deals; but apart from this it affords excellent reading. A plan of the map of the district and several half-tone illustrations embellish this book. “ PHOTOGRAPHY ANNUAL FoR 1897.”’ London: Iliffe and Son, 2s. Gd. net. With each year this annual makes its regular appearance, always full of matters of interest to the . photographic worker. The book is divided into sections, of which there are seven, including tables for reference, lists of photographic societies, practical articles, records of progress, novelties, directories, etc. There are also several excelleut illustrations. ©