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, during the future operations, is placed in contact with the surface which will eventually be the surface of the finished print, it is desirable that it should be smooth and free from blemish; and it should be sufficiently tough to bear the treatment necessary in hot water. Fine Saxe paper answers well.

A solution of India-rubber is used for mounting the tissue. Pure India-rubber should be cut up into fine shreds, and dissolved in pure benzole at the rate of about ten grains to one ounce of the solvent. When properly prepared, it forms a thin varnish, but it leaves a palpable film of India-rubber on the paper to which it is applied. We have at times met with samples which dissolve very tardily in benzole. Where it is found desirable to hasten the complete solution, covering the shreds of India-rubber with a little chloroform will quickly reduce them to a pasty mass, which will be readily dissolved by the addition of benzole.

The India-rubber solution is poured into a flat dish, and the paper floated (till saturated) upon it, or rather drawn over it, so as to secure an even coating on the whole surface. The paper is then hung up by the aid of clothes-clips to dry. The tissue is now floated over the surface of the India-rubber solution in the same manner, care being taken not to allow it to sink below the surface; otherwise the back of the tissue would be coated with the India-rubber, and so retard subsequent operations. The tissue is then hung up to dry for about an hour. When the India-rubber on the paper and on the tissue is dry, the extreme edge of the tissue is