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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The result of my experience is (other things being equal), that cotton prepared in fine dry weather has a greater degree of solubility than when prepared in a moist atmosphere: hence I would recommend the experimenter to choose fine, clear weather for preparing it.

Manipulation.

Having at hand every article requisite, proceed as follows:—Put the nitrate of potash into the mortar or dish; be sure it is dry and well powdered, and then add the acid; stir them well with the pestle and glass rod, so that the lumps will be all (or nearly so) out, and a pasty solution formed. This operation should not occupy more than two minutes' time. Then put in the cotton, about one-quarter of the whole bulk at a time: it should be well picked apart, so that it may come immediately in contact with the acids, and should be kneaded, with the pestle and glass rod, into the solution, and as soon as wetted, another quarter should be added and wetted as soon as possible; so continue until all is in: then knead with the pestle and mortar for at least four minutes, or until every fibre of the cotton is saturated with the liquid; then the mortar should be covered over with the pane of glass, and allowed to stand for fifteen or twenty minutes; then the entire contents of the mortar should be thrown into the pail two-thirds full of water, and stirred with the glass rod as rapidly as possible: if this rapid stirring is omitted, the cotton will be injured by the action of the acids in combining with the water. The water should be poured off, and another change put into the pail.