[TABLE OF CONTENTS.]
| CHAPTER | PAGE | |
|---|---|---|
| I.— | Preliminary Experiments | [1] |
| II.— | Preparation of Albumenized Paper | [6] |
| III.— | The Sensitizing Bath | [13] |
| IV.— | How to Keep the Sensitizing Bath in Order | [20] |
| V.— | Silvering the Paper | [26] |
| VI.— | Washed Sensitive Paper | [31] |
| VII.— | Cutting Paper | [36] |
| VIII.— | Printing-Frames | [42] |
| IX.— | Preparing the Landscape Negative | [45] |
| X.— | Printing the Landscape | [49] |
| XI.— | Preparing the Portrait Negative | [57] |
| XII.— | Vignetting | [60] |
| XIII.— | Printing the Portrait | [69] |
| XIV.— | Combination Printing | [74] |
| XV.— | Toning | [85] |
| XVI.— | Fixing the Print | [92] |
| XVII.— | Washing the Print | [95] |
| XVIII.— | Printing on Plain Paper | [99] |
| XIX.— | Printing on Resinized Paper | [100] |
| XX.— | Printing on Gelatino-Chloride Emulsion Paper | [103] |
| XXI.— | Drying the Prints | [105] |
| XXII.— | Mounting Photographs | [110] |
| XXIII.— | Defects in Prints | [115] |
| XXIV.— | Encaustic Paste | [117] |
| XXV.— | Enamelling Prints | [119] |
| XXVI.— | Cameo Prints | [121] |
| Appendix | [123] | |
[CHAPTER I.]
THEORY OF SILVER PRINTING.
Perhaps it may be wise, first of all, to give the reader some account of the manner in which the subject of silver printing is to be treated, before entering into very minute details, so that it may be followed as a whole, instead of being studied in fragments, a course which is sure to lead to failure, from a want of comprehending what may have been skipped. To understand "the why" and "the wherefore" of every detail is an essential in most occupations, and it is wonderful that photographers are satisfied with the results of rule-of-thumb formulæ, instead of reasoning out their utility. In the following pages most of the theoretical considerations will be brought out in such a manner that everyone will be able to understand them, provided only that there is a slight acquaintance with the name and properties of the chemicals which are dealt with.
PRELIMINARY EXPERIMENTS.
Into a glass beaker put a couple of pinches of common salt, which must be dissolved in a little water.
In a test-tube[1] dissolve about an equal amount of silver nitrate (AgNO3), and add it to the salt solution. We shall find that we have an immediate precipitate, for chloride of silver will be formed by what is called double[2] decomposition, and there will remain in solution a soluble salt known as sodium nitrate. When the silver chloride has settled down, decant off the liquid, and add water to it once or twice, draining off each time. Divide the chloride into four parts, placing each part on a strip of glass. On two of them pour a little common salt solution, and on the other two pour a little solution of silver nitrate; take one of each pair, and place it in a dark cupboard (if warmed, the quicker will be the operation) to dry. Take the other two moist portions of chloride into the open air, and expose them to daylight, and note the results. It will be seen that one of these will darken very rapidly to a violet colour, whilst the other will remain much lighter, though perceptibly blackening. After a time the latter will appear to grow deeper, whilst the former will become a deep black. The one that blackens most rapidly will be found to be that one on which the silver nitrate was poured. Divide the slightly blackened chloride on the strip of glass into two portions, and over one pour a little beer, and over the other a weak solution of potassium nitrite, and again note the difference. It will be found that here the blackening commences anew, but proceeds much more rapidly on that portion over which the nitrite was poured. Here are the experiments. What do they teach?
Potassium nitrite, and silver nitrate, are both inorganic salts, and they both have an affinity for—that is, tend to combine with—any of the halogens (by which are meant such bodies as chlorine, iodine, bromine, and fluorine). In the former case we have silver chloride formed with a little hypo-chlorous acid; in the latter we have a more difficult decomposition: the potassium nitrite is decomposed into hydrochloric acid and potassium nitrate.[3]