=Reversed Negatives.=—In the majority of cases, the resulting copy has to exactly correspond with the original as regards the position left and right, and in such cases the negatives will have to be reversed. This is usually effected in one of four different ways— 1. Reversal of the image by reflection with a prism or mirror, or reversing the plate. 2. Stripping the negative from the glass. 3. By the dusting on or powder process. 4. By the use of negative films. The second is that usually adopted. With regard to the special features desirable in negatives for Collotype, one giving a good silver print will answer equally well for Collotype—they should incline rather to softness than the other extreme. It has been remarked that they should be as free from veil or fog as possible, and may be intensified or not according to the judgment of the operator. =Portraits from Nature=, with their fine half-tone, and at the same time necessary contrast of light and shade, are the most difficult to reproduce in Collotype. The negatives should be perfect in gradation, and such as are usually only obtainable from a talented operator who has the lighting of his studio entirely under his control. =Black and White= subjects, on the contrary, for their satisfactory reproduction, require a negative of the utmost density, but perfectly clear in the lines. Such are better produced by the collodion process, as directed for photo-lithography. For subjects in lines or dots entirely free from half-tone, photo-lithography is more suitable for reproduction than Collotype, where price is a consideration. =Reversal by Reflection=, by means of a mirror or prism, necessitates a special and rather expensive apparatus, and the exposure being somewhat lengthened, it is, although quite successful, more suitable for lifeless objects.