The Optical Magic Lantern Journal (August 1899)

96 The Optical Magic Lantern Journal and Photographic Enlarger. Lantern Slides and Slide Making. Continued from page 89. OR thorough fixation the slide should be left in the solution two or three times as long as it took to clear, and is then examined for density, colour, etc. should be, or, at any rate, only very slightly faulty, the very best remedy is to make another; but if the colour is satisfactory, and the fault only a little reducer is Howard Farmer’s, consisting of 10 per cent. solution of hyposulphite of soda with sufficient 10 per cent. solution of potassium ferricyanide added to turn it a pale yellow. The action must be watched carefully as, if too much of the ferricyanide has been added, it is very rapid, and immediately the reduction is sufficient the plate must be well washed in running water. | | When dissolved, add slowly 1 grain chloride of gold in 1 ounce water. Before toning with this bath the plate must ~ be well washed to remove the fixing solution. If itis not all that it : To tone slides from black to brown, uranium nitrate is used. The formula is :— Uranium nitrate 1 gr. Potassium ferricyanide . ler. Glacia! acetic acid. . 15 mms. Water o 1 oz. With this solution a black coloured slide can | be toned to various shades of brown and finally _ to red; the toning should be carried slightly too much density, it may be reduced. <A good | . clear portions. For washing after fixation I think 2 hours in running water is quite sufficient, and the best form of. washer is one in which the water is : continually passing over the plates. When the | washing is finished, each slide should be given | ' ig reached, the slide is at once washed for 5 a final rinse under the tap, and, while water is running over it, the surface is mopped with cotton wool or gently rubbed over with the fingers to remove any particles or grit which may be adhering to the gelatine ; they are then stood on edge in a warm place, well protected from dust, to dry. If the slide appears of too warm a colour, it can easily be toned with gold. The alpha bath is simple and effective. The formula is :— Hyposulphite of soda . 24 073 Acetate of soda ats $07. Ammooium sulphocyanide to. Gold chloride oe ae . 4grs. Water . 10 ozs. The salts are dissolved in the water in the order given, and the bath will keep for a considerable time in the dark. In toning from brown-red to brown, the slide must be removed and washed as soon as a Slight perceptible toning action has taken place, as the colour is much colder when dry ; for a black the toning must be topped while the slide is still brown-black ; for as _bright blue it may continue until a decided blue colour is obtained, which will be more intense after drying. With this bath slides may be fixed and toned at the same time, or may have been fixed and dried previously. The sulphocyanide bath may also be used, but much stronger than for P.O.P. The formula is :— Water ae oa ns 1 oz. Ammonium sulphocyanide -. 20 gra. if further than the colour required, as there is some reduction of colour in the final washing, which should not be continued longer than is necessary to remove the yellow stain from the The slide should be rather lightly developed, as uranium toning has also an intensifying effect. These colours can be changed to green or blue by immersing the toned and washed slide in a weak iron solution, 1.e., Strong solution perchloride of iron .. 2 mms. Hydrochloric acid .. as 4 mms, Water . 10 drs. As soon as the shade of green or blue wanted or 10 minutes and dried. On removing uranium, toned slides from the washing water they should be gently dabbed over with a pad of soft cambric, free from dust, to absorb as much of the moisture as possible, otherwise the colour will run and spoil the outlines, They are then dried, and, I think, will be found quite permanent. Sieh SPI Saas Optical and Mechanical Effects for the Lantern. — No. X. By EDMUND H. WILKIE. Late Royay Ponyrecunic InstrrvuTion). ( eS Nie vEN 2 producing pictures and effects ne illustrating the setting of the sun or the rising of the moon, the artist on glass has an easy task compared with his brother of the brush, whose work is upon opaque material, for he can by obscuring his picture to the desired extent, render his high lights as powerful and vivid as he pleases. Therefore, slides of this character have always , been favourites with designers of effects, and I think it is not going too far to say that more moonrise effects have been painted than all the other subjects put together.