Make a tin box 18 in. deep, 12 in. high, 12 in. wide, all sides enclosed except one. On the side that is not enclosed, make flange 6 in. wide all round the opening. Cut a hole in the partition where you intend flowing your plates, large enough to admit this box, let the flange fit up against the partition tight, so as not to admit any light. Put an oil stove in this box. It can, by this means, be lighted and turned out without letting light to the plates, and the stove gets what air it needs from the room not used for flowing the plates. Also this plan keeps the smoke from the flowing loom.
Make a tin dish 14 in. long, 8 in. wide, and 3 in. deep. In one end fasten a tin funnel in which a glass funnel holding a pint can be put. Rivet this dish upon top of a tin box, leaving about 2 in. of the end, where the funnel is, extending over the side of tin box, so as to set flowing pitcher under funnel in filtering the emulsion. Put water in this dish and keep it at 140° F. (60° C), while flowing the plates. Set the pitchers containing emulsions in this water. Use a dipping thermometer to tell when the temperature is right. The hot water will be around the tin funnel and keep the emulsion hot while it is filtering. Use a good-sized oil stove, so as to be sure and keep the temperature at 140°-150° F. (60°-66° C), while filtering and flowing.
Screw in top of tables or shelf 3 screw-eyes for each plate; level plates by means of spirit level. In very hot days or climates, it may be necessary to have underneath the shelf a zinc-lined drawer in which ice can be placed; in this case, the shelf above the drawer should be lattice work.
There is another way of working this formula which some might prefer. Take the silvered gelatine, heat it to 150° F. (66° C), ndd the alcohol, albumen, and chrome alum, and let set as before described, but not get dry. Make a bath as follows: -
Ammonium bromide .. 720 gr.
Soda carbonate .. .. 160 gr.
Alcohol ........ 4 oz.
Water ........ 12 oz.
The alcohol in this formula is not absolutely necessary; but when all water is used, it takes longer to get the silver bromide to form. If you do not use the alcohol, employ water instead, and leave the plates in brine longer.
Put this bath into a grooved box the size of plates you wish to make, put the silvered plates in the ammonium bromide bath and let set 24 hours; take them out, put into another grooved box and wash, put them on rack to dry, and they are ready to use; or they can be used wet, but they will be slower.