Black Varnish.—I generally purchase this from the dealer; but I have made an article which answered the purpose well, by dissolving pulverized asphaltum in spirits of turpentine. Any of the black varnishes can be improved by the addition of a little bees'-wax to it. It is less liable to crack and gives an improved gloss.
Negative and Printing Processes.—Being myself an amateur, and desiring to study economy and convenience, my attention has been given to the test of numerous plans for avoiding the necessity of two baths and silvering solutions and I feel confident that the amateur will find the following, in connection with the foregoing Positive Process, the best adapted to his wants.
The same bath and solution is used for the negative as for the positive process; and the time of exposure in the camera should be prolonged a few seconds. I have produced beautiful negatives, in-doors, in four seconds, and, out-doors, instantaneously. The manipulation, bath, and developing solution are precisely the same as those used in the positive process.
Fixing the Negative.—Place the following mixture in a well-stoppered bottle:
| Pure Water | 6 | ounces. |
| Aqua-ammonia, concentrated | 1 | ounce. |
This solution should be poured on the negative and allowed to remain for about twenty seconds. It should be borne in mind, that the developing solution (same as for positives) should be well washed off the glass before the fixing solution is poured over; after it has remained on the glass for the time given (20 seconds), the negative can be washed with clean water and dried; it is then ready for printing. The iodide of silver is not, as in other processes, dissolved off, but remains on the glass.
It sometimes happens that the negative is not sufficiently intense; this result can be obtained by pouring over the plate the following solution, which should remain for about three-fourths of a minute:
| Water | 8 | ounces. |
| Nitrate of silver | 28 | grains. |
| Alcohol | 1 | ounce. |
| Loaf sugar | 1/3 | ounce |
After this solution is used, I pour over the impression the developing solution, and then wash well with water. This re-developing may be repeated two or three times, and almost any desired intensity obtained.