Читать книгу A Practical Manual of the Collodion Process. Giving in Detail a Method For Producing Positive and Negative Pictures on Glass and Paper онлайн

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Yellow vapors sometimes appear when putting the cotton in contact with the solution: this arises from its not being wet; and when they do appear, the cotton where they are should be quickly put under the liquid and kneaded rapidly, which will prevent a continuance of these vapors. I have had them appear, and used the cotton, and could not observe that any bad effect had been produced.

The temperature is worthy the attention of the operator: if it be low, as in winter, and the cotton be left in the nitro-sulphuric mixture for fifteen or twenty minutes, the whole becomes a thick, stiff mass, bedded together, and has not had proper action, giving a bad article. A good temperature is about 140° Fahr. for the last of the time the cotton is in the mixture. This is not always convenient; so the operator will be governed by circumstances, taking his chance of having a good article. In some cases I have heated a thick iron plate, at a moderate temperature, placing the mortar upon it, and thus aided in regulating the temperature. This is the most convenient method I have employed.