After being in use a short time this solution will become weak and should be strengthened by the addition in the evening of a lump or two of cyanide and then stirred up with the dipper in the morning; the negative must not be left in this solution too long or the density of the film will be impaired, but must be removed and well washed directly all the yellow iodide has been dissolved.
THE INTENSIFIER.
| No. 1. | |||
|---|---|---|---|
| Water | 80 | ounces. | |
| Chloride of Ammonium | 2 | ounces. | |
dissolve, then add: | |||
| Bichloride of Mercury | 2 | ounces. | |
dissolve, and filter. | |||
| No. 2. | |||
| Liquor Ammonia 0.880 | 5 | ounces. | |
| Water | 20 | ounces. | |
Solution No. 1 is best kept in an upright holder, as if kept in a flat dish there is always the danger of cutting the skin with the glass plate and getting the mercurial poison into the system.
No. 2 is kept in a well-stoppered bottle and only sufficient for each plate withdrawn as required.
Another method of intensifying, for those who object to the use of mercury, is to bleach the negative in a solution of
| Ferridcyanide of Potassium (Red Prussiate of Potash) | 6 | parts. |
| Nitrate of Lead | 4 | parts. |
| Water | 80 | parts. |
dissolve and filter. {19}
When the plate is bleached, wash it thoroughly under the tap, taking care that the edges and corners of the film as well as the centre are washed, then flood it with a sufficient quantity of
| Nitric Acid | 1 | ounce. | |
| Water | 80 | ounces. | |
Allow this to remain on a fewseconds, then wash, and flood with a sufficientquantity of | |||
| Sulphide of Ammonium | 1 | part. | |
| Water | 5 | parts. | |