The Optical Magic Lantern Journal (September 1890)

30 intended to fit on the top of the microscope, where it could be placed if anything notable were observed in the field. The plates were small, being two and one-eighth of an inch by one and five-eighths of an inch,‘much too small for useful lantern slides. It was capable of taking sharp pictures. The camera used for all my subsequent work was practically the same camera, but elongated about fifteen inches. This gave a picture about three inches square, and yet was sufficiently short to allow working all the microscope adjustments while focussing the picture. For convenience and Steadiness the camera (except in special cases) was arranged parallel with the table, instead of being placed on the microscope and regardless of the position of the latter. “At the outset it may be well to disclaim any idea in connection with these slides to be shown other than that of lecture diagrams. In many cases detail, &c., was deliberately suppressed, and some appearances exaggerated to make the remainder more diagrahpic, but there was nothing more done than would be allowed in the staining and mounting of the specimens, had they been specially prepared with the intention of taking photographs trom them. Some which were mounted with that intent were so stained as only to exhibit the particular point wished to be shown, and to keep the remainder of the tissue only suggested. ‘The actual photographic work was in most cases easy, the ordinary methods being employed ; in other cases, however, the special isochromatic plates were necessary onaccount of the stain employed in mounting the sections. “The greatest difficulty was in the selection of the objects to be photographed. We all know that it is possible to cut fifty or a hundred sections of almost any ussue, and give one to each member of a class, each student receiving a fairly typical section, sufficient to demonstrate the various points described ; but if we were restricted to a point in one section, such as occurs when a photograph is indicated, there might not be a single specimen in these sections that would be quite Satisfactory. Hence I had to exercise more care in the selection of the slide than anything else, and in some Instances to delay a considerable time before! obtained a sufficiently good section tomake a diagram. In other cases I found a special process useful in more closely imitating the colours of the stained sections, which I shall now briefly describe. “ During the early part of 1889 I was shown some beautiful photographs on Leisgang’s aristotype paper of the spinal cord taken by Dr. Ringrose Atkins, of Waterford. They were of sucha brilliant tint as to give a very correct idea of the original specimens when treated by some staining agent. Some correspondence ensued between us, in which he very kindly explained the process he had adopted. I made a few modifications in the process, adapting it specially for lantern slides, and then found that the process could be extended into other colours. _ ‘Dr. Aucins’ process consisted in toning the silver image with ferro-cyanide of uranium, the completed slide well washed in alum to remove the sodium. This sulphate from the gelatine was placed in a bath composed of equal parts of a r or 2 per cent. solution of potassium ferrid cyanide (Xv Fe: Cn), and a 6 per cent. solution of uranium nitrate. M. HEDLEY. (To be continucd.) The Optical Magic Lantern Journal and Photographic Hularger. A Few Hints on Amateur (Comic) Slide Making. i! THESE few lines are written chiefly for the pure amateur. Many amateurs, as they please to style themselves, run the professionals very close, and can afford to skip this article. I wish to be brief and spare the excited amateur—they generally are excited over their hobby—the time and trouble of reading useless matter. All I hope for in again bringing this subject forward is that I may possibly manage to clear a few doubts that may have remained after perusing former articles. Regursites.—3}in. by 3tin. glasses, Indian ink, crowquill pen, subjects to copy, paints, varnish, and for some slides I find a good thing to throw up effect of slide, dense black varnish. All of these may be obtained at any vendor of lantern articles, except subjects to copy. One word of warning: mind the paints you buy. Buy boxes of paints expressly made for the purpose of painting slides. I obtained a yellow once sazdé to be transparent. I used it as yellow, andI mixed it with my green; the result, when I tried the set of five slides, was, to Say the least, painful. Concerning subjects, there is now no need to be at aloss. The Boys' Own Paper supplied me at times ; Pick Me Up and other weeklies often gave a suitable picture. The amateur, however, does not want to have the trouble. of reducing the pictures, so if he wants a good selection of suitable sized pictures let me recommend the new halfpenny weekly, Come Cuts. Choose your picture, clean your glass. I cannot afford luxuries, and so just wipe it clean with linen duster after washing. Mix a little Indian ink, say in an inverted egg-cup. Lay glass over picture on a flat table. Trace outline with your fine pen and Indian ink. Breathing on the glass aids the flow of ink. Take care, however, as the outline is being traced that the eye is kept directly over point of pen, otherwise the thickness of glass will cause the picture to be out of all proportion. The thicker the glass the greater the disproportion. If you are doing a series or set, outline all of them first. I say this because it will save both time and paint when you come to colour them, for when you have a colour mixed common to all, you can lay that colour on each glass before mixing another. It may also save you the mortification of finding that in one slide a boy’s cap or jacket are one colour, and in another slide of same set the colour has altered. Now the amateur must have a desk to paint on. One I made cost about threepence. If you go to buy they will charge you twelve to twenty times as much ; and as the magic lantern is a costly hobby, make your own desk. Get a flat lath (used for | blinds) and a piece of plain glass, Gin. by Gin. ; take two pieces of lath, 9in., for sides; two others, 6in., for top and bottom; nail together so as to leave space for glass. In the inside of top and sides I nailed small pieces for glass to rest on, and on upper surface held glass in place with small tacks or nails. Across bottom of glass I nailed a flat strip to ledge slide on, and on each side another strip, 7in., for rest, and allow easel to slope in any position. It may be placed on a table-cloth, and will not slip, and a piece of white paper under it