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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I will here remark that, since the first edition, I have had occasion to use large quantities of soluble cotton, and have found that if it be kept in an atmosphere of alcohol and ether, its solubility is somewhat improved: that is, in the case of its not being used immediately after its preparation. This is easily kept, by dropping a few drops of ether or alcohol into the bottle containing it, and then sealing close until wanted for use. In the event of the water being displaced by alcohol, it is not necessary to thoroughly dry it, but put in a perfectly close bottle to keep.

Remarks.—There are a few precautions necessary to be observed in the preparation of soluble cotton. I should select a fine clear day, if time is no object; nevertheless I have made a good article in a moderately dense atmosphere. Sulphuric acid has a powerful affinity for hydrogen, consequently, in damp weather, it is more or less reduced by the moisture in the air.

It is advisable to prepare the nitro-sulphuric acid mixture on a roof, or between two doors or windows, where there is a good current of air, in order to prevent the inhalation of white vapors which arise, and are very poisonous to the lungs. As a preventive, in case of inhaling these vapors, I apply the fumes of aqua-ammonia. It is best for every one to have six or eight ounces of this always at hand; it neutralizes all acid that maybe spattered on the clothes, prevents its destructive powers, and restores the color.