=Pumphrey’s Lifting Films= are the latest and best of a series of films introduced by the same maker. They consist of a basis of paper coated with a waterproof varnish on one side, upon the other being spread an indiarubber coating possessing considerable adhesive power; to this is attached the gelatine film proper, which consists of two layers, one of plain gelatine, and the other the sensitive emulsion. The films should be exposed in the camera between two glass plates, and the spring of the dark slide should be of considerable strength to insure flatness of the film, and consequent sharpness of the image. The films during development may be treated exactly as an ordinary plate, the manufacturer recommending Beach’s developer. When in the bath they seem little liable to damage, and may be handled with great freedom and facility. Upon completion of the development, fixing, and washing, the paper backing or support is attached by means of paste to a substantial and smooth card. As a precaution, not always necessary, but usually advisable, against the film prematurely separating from its support, around the edges gummed paper strips may be attached to the card, and allowed to extend over the edges of the gelatine film to the extent of 3 mm. When dry the film may be varnished, and afterwards lifted from its support by first cutting through the gelatine and passing the blade of the knife round the edges between the film and the temporary paper backing, the latter remaining attached to the card. The two are by these means readily separated, and the resulting negative film may be printed from either side without disadvantage, and is of sufficient strength to withstand a considerable amount of rough handling. =Other Methods of Reversal.=—There are processes of copying, usually by first producing a transparency and from that again a negative. If the wet process is used throughout, a copying camera is essential in both stages. Should dry plates, however, be used, the transparency may be produced in the camera and the negative by contact in a printing frame, or _vice versa_, or both may be produced by means of the camera. If the transparency be produced by the carbon process a negative may then be made from it by contact, and the necessary reversal will be brought about without the use of the copying camera. CHAPTER VIII. PRINTING IN THE PRESS.