| 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.
| Focus of Lens. In. | 1 inch | 2 inches | 3 inches | 4 inches | 5 inches | 6 inches | 7 inches | 8 inches |
|---|---|---|---|---|---|---|---|---|
| 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.
To make a good enlargement five points should be kept constantly in view, viz.:
1. Most careful treatment of the original negative.
2. Making a diapositive complete in all its parts.