Fix the plate in hypo--the fixing takes place very quickly--then examine the picture for the faults above described; if they are found, wash the plate under the tap gently, and bring into operation a camel's hair brush and a weak solution of cyanide of potassium. Apply the brush to the over-printed parts, taking care not to work on the places that are not too dense. Do not be afraid to use plenty of washing while this is being done; let it be, as it were, a touch of the brush and then a dash of water, and you will soon reduce the over-printed parts. It only requires a little care in applying the brush. After this wash well, and should it be deemed necessary to tone to a black tone, use a weak solution of bichloride of platinum and chloride of gold, or a very weak solution of iridium, in equal quantities, allowing the picture to lie in the solution till the color has changed right through to the back of the glass. Should a warm pinkish tone be desired, I tone with weak solutions of ferri cyanide of potassium, nitrate of uranium, and chloride of gold in about equal quantities. After toning, wash well and dry; they dry quickly. Varnish with Soehnee crystal varnish, then mount with covering glasses, and mark. Bind round the edges with paper and very stiff gum, and the picture is complete. The making of a really good transparency is by no means an easy or pleasant task with a wet collodion plate, but with these dry plates an amateur can, with a little practice, produce comfortably slides quite equal to those procurable from professional makers. * * * * * THE HONIGMANN FIRELESS ENGINE.