(Obernetter's.)
"Place the copper plate in a porcelain tray on the bottom of which rests a brightly burnished copper wire, the negative pole.
"The anode on the positive pole, a bright steel plate, is suspended over the copper plate, and kept in motion while the circuit is closed. A precipitate of steel, resembling silver in appearance, must instantly occur upon the copper plate, any air-bells to be removed. Five minutes is sufficient to deposit a perfect steel coating." Grease the plate after steel facing, to keep off the rust. Formula:
(Obernetter's.)
| Distilled water | 1 litre |
| Chloride of ammonium | 60 grammes |
| Proto sulphate of iron | 30 grammes |
| Iron alum | 30 grammes |
CHAPTER IX.
Materials Necessary for Photogravure, and List of Firms Supplying them.
Materials.
Printing Frame (deep), 8 × 10, screw pressure, $8.
Roll Carbon Tissue, No. 100; Standard Brown, $3.
Johnson Actinometer, $1.25.
Beaumé Hydrometer, $1.25 (with glass).
Silver " (argentometer) 75c.
Engravers' Scraper, $1.75, best grade.
" Burnisher, $1.75, "
Powder Box for graining (paste-board), $1.
Powdered Syrian Asphaltum, $1 per pound.
Nine (9) pounds Perchloride of Iron (C. P. crystals), 45c. per pound.
Stick Rouge, 20c.
Turpentine, 20c. (refined).
Alcohol (95 per cent.).
Modeling Wax, $1.25.
One Ps. Scotch Stone, 25c.
One dozen Glass Blowers' Charcoal, $2.0c per dozen sticks (for polishing copper).
One pound Absorbent Cotton, 50c.
One pound Caustic Potash C. P. (sticks).
One Porcelain Tray, deep, 11 × 14, $3.50.
One Florence Hand Lamp, 75c.
One Squeegee.
Three Roulettes, $1.50 each.
Hand Vise, 75c.
Calipers, 50c.
Dairy Thermometer, 25 c.
One bottle Etchers' Varnish, 50c.
One ounce Chloroform, 20c.
Six ounces Bichromate Potassium.
One pound Concentrated Ammonia.