Every imaginable pattern of darkroom lamp has been placed on the market, and with some of these efficiency is not always commensurate with the price. We have developed many thousands of plates and films with the aid of pyramid nightlights in an ordinary hock bottle costing one shilling. When oil is the illuminant it would be advisable to see the pattern of lamp in use before purchasing; many such lamps have a disconcerting way of bubbling when the surroundings of the burner get heated. If much work is done we recommend a lamp of similar kind to that illustrated, in which no direct rays of light can possibly reach the plate. Indeed, a lamp on this principle is almost indispensable with ortho-chromatic and colour-sensitive plates. As a further precaution we would suggest that this lamp should be placed on a shelf above the developing table. In this way the whole of the dark room will be fairly well illuminated, so that there will be no need to grope along the shelves for anything forgotten, and yet the risk of fogging plates will be minimised. The source of light may be either electricity, gas, hard wax candles, or oil; but if the latter is employed the burner must be a good one and capable of being regulated from outside. The glass fronts are interchangeable, orange-yellow and ruby being usually employed, though ruby is now often replaced by other tints, equally non-actinic in practice, and less trying to the eyesight. For ortho-chromatic plates even ruby glass allows too much light at the red and yellow end of the spectrum to be transmitted, and it is necessary to qualify it with methyl-violet or to employ one or other of the "safe light" screens manufactured by Messrs. Wratten & Wain-wright. Paper screens have to be replaced very frequently, as they fade in the damp atmosphere of the dark room.
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 enlargements 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 are 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, 10 per cent. solution.
Potassium bromide, 10 per cent. solution.
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.
Fig. 2. Safe Lamp For Dark Room.