partially sacrificed, the solubility of the albumen layer in cold water being impaired. Photo-lithographic transfer paper prepared as above described has been for some time in the market, and may be procured as an article of commerce, in an unsensitised condition; it will keep indefinitely in this state, and may be sensitised as required. The surface should not be allowed to remain in contact with the bath, neither should the immersion be lengthy, as in either case the surface of the paper would probably suffer. After drying by suspending by one corner in the dark, the chromated paper is exposed under a suitable negative—if possible to the sun—for a few minutes only; it may be examined by non-actinic light, and when the image appears brown or grey upon a yellow ground, and all details are visible, it is removed from the copying frame and entirely covered with a thin coating of transfer ink. This as purchased is much too stiff for use, and must be reduced by means of turpentine to such a consistency that it is possible to distribute an even and quite thin layer upon the surface of the print, without its penetrating to the paper. The ink should be so thin that it presents a grey, not black, appearance. [Q] For instance, the double transfer paper as used in the carbon process.—TRANS. Those who may find it necessary, or who care to prepare their own ink, should take—chalk ink (printing) 4 parts, beeswax 10 parts, resin 7 parts, turpentine 40 parts, tallow 8 parts, Prussian blue 6 parts, ground and mixed in a paste. The chalk printing ink should be melted by gentle heat, then add the wax and resin in a molten condition, then the tallow, and lastly the Prussian blue and turpentine; on account of the inflammable nature of the latter these operations should not be conducted at an open fire. If, after prolonged keeping, this ink becomes tough, and does not readily leave the transfer paper when transferring to stone, the addition of a few drops of olive oil will restore it to a usable condition. The ink is best applied by means of a fine, dry sponge,[R] with which it should be spread on the transfer as evenly as possible, during which operation the print must be protected from actinic light; on its completion the print is placed aside to allow the turpentine to evaporate. This in a warm room will be about ten to fifteen minutes; the print is then placed in cold water, care being taken to remove any air-bubbles from its surface. After remaining for about half an hour the uppermost layer will have become sufficiently loose to allow of its removal, together with the adherent ink not forming part of the picture, upon the application of slight friction. [R] A smooth composition roller answers equally well.—TRANS.