The Optical Magic Lantern Journal (May 1895)

83 The Optical Magic Lantern Journal and Photographic Enlarger, matter with it. For photographic use all natural waters should be well boiled and allowed to subside or be filtered. Water purified by distillation is the best for all chemical purposes. water sold as distilled water is far from pure, being contaminated by the vessels in which it has been stored —from the luting of the | apparatus in distilling it, or from some other reason that could have been prevented by care. Good distilled water should be bright and odourless, and not show the least Opalescence on the addition of silver nitrate. Should it be at all turbid or have the least smell, it may be safely concluded that it is impure, even if the silver nitrate test is satisfactory. Organic matter of some kind is in all probability contained in it. Lead is more easily corroded and dissolved by pure contains nitrate, carbonates, and sulphates. Distilled water, therefore, should never be stored in lead receptacles ; glass or well glazed earthen| ware is best. Distilled water procured from the condensing engines of steamers or manufacturers’ stationary engines is rarely free from oily matter ; sometimes it is fairly good, but at | At any rate, it will not be | others far from it. wise to trust to the purity of water obtained from such sources. The water supply of most large towns is tolerably pure, but it should not be used for photographic purposes, such as development, without filtering it through two or three thick. nesses of finc flannel, or swansdown calico. A bag of this material may be fixed over the supply tap and form a permanent filter, taking it offand washing occasionally is all the atten. tion required. It is surprising, even when the It often happens that | water than if it j water seems bright and good, what a quantity of foreign matter will soon accumulate in this bag. It should also be boiled and allowed to stand before use. negatives, and sometimes fogging, may be traced to the use of impure water when its may have been all it should be. As a matter of course any defect in a lantern slide is enlarged ; those that would pass muster in an ordinary printing negative would ruin a transparency ; therefore, any little extra trouble in ascertaining the water is not at fault is amply repaid by the clear, neat, and finished appearance of the slide. 20: From an advertisement on another page it will be seen that Mr. Alfred Meager is now booking engagements for exhibition for the next season Mr.’ Meager is, so to speak, a past master in the lanterniuc line. appearance | the screen it will have a natural effect, ; not appear, as too many lantern pictures Notes on Lantern Slide Making. By T. Prrxins. A SHORT time ago, while I was engaged in the preparation of a lantern lecture, a large number of slides by various workers passed through my hands. They were of all qualities, some eminently beautiful, some good, many indifferent, and a few bad. The average character, however, of the slides confirmed my conviction that | the making of a really good lantern transparency ' 18 by no means the easy matter it looks on ~ paper. , Out some of the defects most I intend in the present article to point frequently met with, and to suggest how they may be avoided. | But first we must enquire what constitutes a perfect slide. To this the answer must be :— Complete gradation from the deepest shadow which must not be absolutely opaque, to the highest lights which should’ be clear glass ; moreover, the highest lights must occupy a very small area of the slide. Ruskin gives some admirable advice on this matter to painters, which may be equally taken to heart by photographers when he says ‘‘ Make your whites precious and your blacks telling.” As an instance of the observance of this rule, as far as the lights are concerned, he points out a wellknown picture by Correggio, ‘‘ The Cupid, Venus and Mercury,” in the National Gallery, where the only pure piece of white is a spot of paint on one of Cupid’s wings about the size of a pin’s head, but of great luminosity owing to the subtle way in which this spot is led up to through gradations of half-tones of ever-increasing bright ness. Compare this picture with the blank white skies in many lantern slides, and the inferiority of the latter is evident. If, however, the photographer can secure perfect gradation : in his negative, and retain it in reversed order Many of the defects on ; = in his transparency, he will get a luminous whole, so that when the picture is thrown upon and that we see do appear, as if they were intended to represent Nature as seen by the light of an electric lamp. To secure this effect, a good negative is indispensable. It must be full of soft detail, but at the same time neither flat nor over thin, or the slide itself will be flat. No fixed rules can be laid down for the colour of a perfect slide, much depends on the subject, something also on taste. One thing, however, may be said, namely, that many commercial slides made on wet collodion have a