Another formula for intensifying is one which can be used as soon as the plates have been developed and fixed, and gives the required strength to quite thin negatives. This is prepared in three solutions, and used in the same way as the first formula given. No. 1, bichloride of mercury, 2 parts; water, 100 parts. No. 2, iodide of potassium, 3 parts; water, 33 parts. No. 3, sodic acetate, 4 parts; water, 33 parts.
Caution: Mark all bottles containing intensifying solutions "Poison," be very careful in handling, and keep them locked up when not in use. Bichloride of mercury (corrosive sublimate) is a violent poison, and a grain or two of it taken internally may prove fatal. An antidote is the whites of eggs beaten up with water and given promptly, repeatedly, and abundantly. The albumen of the egg renders the salts of mercury insoluble, and enables the stomach to throw off the poison instead of absorbing it into the system.
Mlle. C. de Gramont, Paris, France, asks "If an amateur can make a non-halation plate, and how, and what is the best method of sensitizing the salted paper described in No. 796?" Plates already sensitized can be covered, rendered almost free from halation by painting the back or glass side with a mixture of collodion and rouge. In place of the rouge any dark red or brown pigment may be used. The mixture dries quickly, and is easily wiped off the plate before developing. Another mixture may be made of ½ oz. gum-arabic, 1 drachm of glycerine, ½ oz. burnt sienna, and 5 oz. water. Heat enough of the water to dissolve the gum-arabic, and when cold mix all the ingredients together. Apply with a brush. After exposure and before developing it should be wiped off the plate with a cloth wet with benzine. In No. 803 will be found further directions for preparing plain salted paper. The easiest way to sensitize the paper is to cut it into 8 by 10 sheets, lay a piece on a pane of glass, holding it from curling by two or three letter-clips; or, if preferred, a smooth board can be used and the paper fastened to the board with small thumb tacks. Apply lightly and evenly, first one way and then the other at right angles. Be sure that all the paper is covered. Dry in a dark room, pinning the paper to the wall or some smooth surface. After two or three times trying one can apply the solution evenly. The prints are very beautiful, and if well washed do not fade.
Answers to several correspondents.—We have had many queries as to how one may become a member of the Camera Club. Any member of the Round Table may become a member of the club by sending his or her name to the Round Table. We hope all of our readers who own cameras will join the club, as we expect to give some new and original plans for work during the year.
Sir Knight B. P. Atkinson, Tilton, New Hampshire, asks, 1. What is Eikonogen made from, and what is the chemical name. 2. What is the difference between chrome alum and alum crystals. 3. When we expect to have another photographic contest. 4. Is Watkin's exposure meter a reliable machine. 5. How can films be kept from curling.
1. Eikonogen is the sodium salt compounded from three different chemicals, and comes in whitish-gray crystals. It is the name of a developing agent patented by Dr. Andreson about six years ago. It is not poisonous, does not stain the fingers, and gives a clear negative with plenty of detail. 2. The difference between chrome alum and alum crystals is principally that chrome alum has twice the strength of alum crystals, being a double salt, instead of the commercial alum usually sold. Both chrome alum and alum crystals are used for the same purpose in photography, for clearing and hardening the film of the negative. 3. The date has not yet been fixed for our next photographic contest, but we intend to have another soon. 4. It is out of our province to pass judgment on any kind of photographic apparatus. 5. Films may be kept from curling by soaking them after they have been developed and before they have been dried, in a solution of glycerine, ½ oz., distilled water, 16 oz., for five minutes, and then drying as usual.
