It is not very difficult to improvise a portable red lamp for use when changing plates on a holiday. A sheet of ruby paper, pinned into cylinder form round a night light, will serve fairly well. If no ruby paper is available a trial might be made of blotting paper soaked in red ink, and, when dried, rubbed with vaseline or butter to render it translucent.
At proper intervals the safety of the dark room and lamp should be carefully tested. Place a plate in the dark slide. Lay the slide on the developing table, and half withdraw the shutter. After about a minute and a half develop the plate in the usual manner ; and if within three or four minutes it becomes discoloured there is urgent need for reform.
A series of glass measures, varying in size from a quarter ounce (marked with minims) and a two-ounce (marked with drams) to a ten-ounce, or even a pint measure when enlarge ments are attempted, should stand on a convenient shelf with a glass funnel close beside them. For developing and fixing dishes in the smaller sizes earthenware is the best material. For larger sizes we prefer enamelled steel, as they
may be stacked out of the way when not in use without fear of breakage. Draining racks for plates are a most useful adjunct, especially the square pattern, which may be lifted from a fixing tank into a washing-trough, and thence taken out to dry without the necessity of separate handling. Weights and scales, filtering papers, packets of plates, and dry chemicals arc best stored in some cupboard protected from damp, and not in the dark room. The following chemicals should, however, always be readily accessible, in addition to the developing, etc., solutions favoured : Alum, io per cent. solution.
Potassium bromide, to per cent. solution. Nitric acid.
Ammonia, •880.
Formalin.
The bottles should be etched, or bear indestructible labels ; and in the case of the three latter a small bottle is preferable for safe and easy handling. If a large bottle of either of the two last happened to get broken, the dark room would be rendered untenable for a lengthy period.