wunder · LibraryPart 352
Read in the Wunder reader — freeImmediately before the toning, mix
Solution A 200 cubic centimeters Glacial acetic acid 20 cubic centimeters Solution B 200 cubic centimeters Solution C 30 to 40 cubic centimeters
Brown tints. Use the following solutions: {542}
A.—Uranium nitrate 12 grams Water 1,000 cubic centimeters
B.—Red prussiate of potash 9 grams Water 1,000 cubic centimeters
And mix immediately before use
Solution A 100 cubic centimeters Solution B 100 cubic centimeters Glacial acetic acid 10 cubic centimeters
Pictures toned in this bath are then laid into the following solution:
Water 1,500 cubic centimeters Pure hydrochloric acid 5 cubic centimeters Citric acid 20 grams
«To Turn Blueprints Brown.»—A piece of caustic soda about the size of a bean is dissolved in 5 ounces of water and the blueprint immersed in it, on which it will take on an orange-yellow color. When the blue has entirely left the print it should be washed thoroughly and immersed in a bath composed of 8 ounces of water in which has been dissolved a heaping teaspoonful of tannic acid. The prints in this bath will assume a brown color that may be carried to almost any tone, after which they must again be thoroughly washed and allowed to dry.
«COMBINED TONING AND FIXING BATHS.»
The combined toning and fixing bath consists essentially of five parts—(1) water, the solvent; (2) a soluble salt of gold, such as gold chloride; (3) the fixing agent, sodium thiosulphate; (4) a compound which will readily combine with “nascent” sulphur—i. e., sulphur as it is liberated—this is usually a soluble lead salt, such as the acetate or nitrate, and (5) an auxiliary, such as a sulphocyanide.
The simplest bath was recommended by Dr. John Nicol, and is as follows:
Sodium thiosulphate 3 ounces Distilled water 16 ounces
When dissolved, add
Gold chloride 4 grains Distilled water 4 fluidrachms
A bath which contains lead is due to Dr. Vogel, whose name alone is sufficient to warrant confidence in the formula:
Sodium thiosulphate 7 ounces Ammonium sulphocyanide 1 ounce Lead acetate 67 grains Alum 1 ounce Gold chloride 12 grains Distilled water 35 fluidounces
A bath which contains no lead is one which has produced excellent results and is due to the experimental research of Dr. Liesegang. It is as follows:
Ammonium sulphocyanide 1/4 ounce Sodium chloride 1 ounce Alum 1/2 ounce Sodium thiosulphate 4 ounces Distilled water 24 fluidounces
Allow this solution to stand for 24 hours, during which time the precipitated sulphur sinks to the bottom of the vessel; decant or filter, and add
Gold chloride 8 grains Distilled water 1 fluidounce
It is curious that, with the two baths last described, the addition to them of some old, exhausted solution makes them work all the better.
«ENLARGEMENTS.»
─────────────────────────────────────────────────────────────────────────────── TIMES OF ENLARGEMENT AND REDUCTION ───────+────────+────────+────────+────────+────────+────────+────────+──────── Focus │ │ │ │ │ │ │ │ of │ 1 inch │2 inches│3 inches│4 inches│5 inches│6 inches│7 inches│8 inches Lens. │ │ │ │ │ │ │ │ In. │ │ │ │ │ │ │ │ ───────+────────+────────+────────+────────+────────+────────+────────+──────── 2 │ 4 │ 6 │ 8 │ 10 │ 12 │ 14 │ 16 │ 18 │ 4 │ 3 │ 2 2/3 │ 2 1/2 │ 2 2/5 │ 2 1/3 │ 2 2/7 │ 2 1/4 ───────+────────+────────+────────+────────+────────+────────+────────+──────── 2 1/2 │ 5 │ 7 1/2 │ 10 │ 12 1/2 │ 15 │ 17 1/2 │ 20 │ 22 1/2 │ 5 │ 3 3/4 │ 3 1/3 │ 3 1/8 │ 3 │ 2 9/10│ 2 6/7 │ 2 3/16 ───────+────────+────────+────────+────────+────────+────────+────────+──────── 3 │ 6 │ 9 │ 12 │ 15 │ 18 │ 21 │ 24 │ 27 │ 6 │ 4 1/2 │ 4 │ 3 3/4 │ 3 3/5 │ 3 1/2 │ 3 3/7 │ 3 3/8 ───────+────────+────────+────────+────────+────────+────────+────────+──────── 3 1/2 │ 7 │ 10 1/2 │ 14 │ 17 1/2 │ 21 │ 24 1/2 │ 28 │ 31 1/2 │ 7 │ 5 1/4 │ 4 2/3 │ 4 3/4 │ 4 1/5 │ 4 1/12│ 4 │ 3 9/10 ───────+────────+────────+────────+────────+────────+────────+────────+──────── 4 │ 8 │ 12 │ 16 │ 20 │ 24 │ 28 │ 32 │ 36 │ 8 │ 6 │ 5 1/3 │ 5 │ 4 4/5 │ 4 2/3 │ 4 4/7 │ 4 1/2 ───────+────────+────────+────────+────────+────────+────────+────────+──────── 4 1/2 │ 9 │ 13 1/2 │ 18 │ 22 1/2 │ 27 │ 31 1/2 │ 36 │ 40 1/2 │ 9 │ 6 3/4 │ 6 │ 5 3/5 │ 5 2/5 │ 5 1/4 │ 5 1/7 │ 5 1/16 ───────+────────+────────+────────+────────+────────+────────+────────+──────── 5 │ 10 │ 15 │ 20 │ 25 │ 30 │ 35 │ 40 │ 45 │ 10 │ 7 1/2 │ 6 2/3 │ 6 1/4 │ 6 │ 5 5/6 │ 5 5/7 │ 5 5/8 ───────+────────+────────+────────+────────+────────+────────+────────+──────── 5 1/2 │ 11 │ 16 1/2 │ 22 │ 27 1/2 │ 33 │ 38 1/2 │ 44 │ 49 1/2 │ 11 │ 8 1/4 │ 7 1/3 │ 6 4/5 │ 6 1/2 │ 6 5/12│ 6 2/7 │ 6 3/16 ───────+────────+────────+────────+────────+────────+────────+────────+──────── 6 │ 12 │ 18 │ 24 │ 30 │ 36 │ 42 │ 48 │ 54 │ 12 │ 9 │ 8 │ 7 1/2 │ 7 1/5 │ 7 │ 6 6/7 │ 6 3/4 ───────+────────+────────+────────+────────+────────+────────+────────+──────── 7 │ 14 │ 21 │ 28 │ 35 │ 42 │ 49 │ 56 │ 63 │ 14 │ 10 1/2 │ 9 1/3 │ 8 3/4 │ 8 2/5 │ 8 1/6 │ 8 │ 7 7/8 ───────+────────+────────+────────+────────+────────+────────+────────+──────── 8 │ 16 │ 24 │ 32 │ 40 │ 48 │ 56 │ 64 │ 72 │ 16 │ 12 │ 10 2/3 │ 10 │ 9 3/5 │ 9 1/3 │ 9 1/7 │ 9 ───────+────────+────────+────────+────────+────────+────────+────────+──────── 9 │ 18 │ 27 │ 36 │ 45 │ 54 │ 63 │ 72 │ 81 │ 18 │ 13 1/2 │ 12 │ 11 1/4 │ 10 4/5 │ 10 1/2 │ 10 2/7 │ 10 1/8 ───────+────────+────────+────────+────────+────────+────────+────────+────────
{543}
The object of this table is to enable any manipulator who is about to enlarge (or reduce) a copy any given number of times to do so without troublesome calculation. It is assumed that the photographer knows exactly what the focus of his lens is, and that he is able to measure accurately from its optical center. The use of the table will be seen from the following illustration: A photographer has a carte to enlarge to four times its size, and the lens he intends employing is one of 6 inches equivalent focus. He must therefore look for 4 on the upper horizontal line and for 6 in the first vertical column, and carry his eye to where these two join, which will be at 30–7 1/2. The greater of these is the distance the sensitive plate must be from the center of the lens; and the lesser, the distance of the picture to be copied. To reduce a picture any given number of times, the same method must be followed; but in this case the greater number will represent the distance between the lens and the picture to be copied, the latter that between the lens and the sensitive plate. This explanation will be sufficient for every case of enlargement or reduction.
If the focus of the lens be 12 inches, as this number is not in the column of focal lengths, look out for 6 in this column and multiply by 2, and so on with any other numbers.
Henley's Twentieth Century Formulas, Recipes and Processes · The Wunder Library — complete classics, free to read, with narration.