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 for drying at 16° Beaume, is about one hour. The separation is performed as described above. The benzine is applied on the side of the caoutchouc paper.

The conditions for the success of this process are: a soft caoutchouc paper, a good caoutchouc solution, well-sized paper, and strong pressure.

Careful drying is important, and strong rubbing in with benzine. If, however, in separating, some parts of the picture should tear, and the whole picture should be difficult to separate, then it is better to stop the separation at once, to place the picture into a glass or tin dish, to place a piece of plate-glass upon the picture in order to press it, and to pour benzine upon them until they are covered.

To avoid the evaporation of the benzine, place the dish with the pictures into a larger dish, which fill for about one-quarter of an inch with water, and now place over the dish containing the pictures, another one inverted, which will dip with its sides in the water, and prevent evaporation. The pictures remain in this for about ten minutes, when they can be easily separated.

All pictures must, on account of the caoutchouc which attaches itself to them, be rubbed off with a piece of flannel saturated with benzine.

When the picture on caoutchouc has been thickly gelatinized (12 per cent, gelatine), it will be easy to remove it from the paper as a pure film.

This circumstance led me to experiment, to transfer the carbon (pigment) picture to glass, and the experiment succeeded perfectly. For this purpose, I covered the picture resting on the caoutchouc, thickly with a solution of gelatine: