A Manual of the Collodion Photographic Process - Preperation of Gun Cotton
Contents
Part 1
Part 2
- Preparation of Collodion Film
- Immersion of Plate in the Bath
- Exposure of the Prepared Plate to the Action of Light
- Development of the Image
- Fixing of the Image
PART III
- The Whitening Process
- The Camera
- Description of the Camera
- Glass Bath
- Photographic Lens
- Summary of Precautions
- Conclusion
Preperation of Gun Cotton
- Take of dry nitre in powder .................40 parts
- Sulphuric acid ......................................60 parts
- Cotton .....................................................2 parts
The nitre, sulphuric acid, and cotton, are weighed in the above proportions, and placed near at hand, within reach of the operator, to Prevent delay in mixing when the operation has commenced.
First put the powdered nitre into a basin placed firmly, so that there shall be no fear of its upsetting: it is necessary that this operation should be conducted either in the open air or in some convenient situation where there is sufficient draught to carry off the nitric acid vapour generated. ‘Then pour the proportion of sulphuric acid into the powdered nitre, stirring them well together for a few seconds, with a strong glass rod. Immediately the two are mixed add the cotton, having previously pulled out the fibres, and mix them well together with two glass rods, in order that the whole of the cotton may come in contact with the nitric acid vapour, which is being rapidly generated from the mixture.
This action must be continued for about two minutes; then quickly remove the cotton with the adhering nitre and sulphuric acid from the basin, with the glass rods, and plunge it into a large quantity of water; it is to be well washed in repeated changes of water until all the acid and nitre are washed away.
The cotton is then collected together and first pressed between the hands to drain off the water, and then still further dried by pressure in a cloth; the fibres of cotton can now be carefully separated and hung up with pins to the edge of a shelf or any other conve- nient place to dry. There is no necessity to use artificial heat, as the small quantity requisite for a few ounces of solution can easily be dried without it.
The next receipt is by certain proportions of nitric and sulphuric acids:
- Take 1 oz. by measure of nitric acid, S. G., 1°450
- 1 oz, a sulphuric acid ordinary
- 80 grs. by weight of cotton.
The fibres of cotton must be well separated as in the preceding mode. The two acids are first mixed, and the requisite proportion of cotton added as quickly as possible, and well stirred with two glass rods for not more than fifteen seconds: the gun cotton is removed from the acids, and plunged into water to undergo the same washings, &c. as in the former recipe.
It will be seen that the cotton is not ex- posed to the action of the mixed acids, in this last mode, longer than is necessary to saturate the cotton; should the action be continued further, the solubility of the cotton is entirely lost.
Water must not be spared in washing the cotton, for not a trace of acid should be left ; the collodion would be injured by any remaining.