Intensifier. This term is used to denote those substances which, when applied to a negative, serve to increase the actinic opacity of the deposit already formed. One class of intensifies acts by increasing the deposit of silver forming the image. To this class belongs a mixture of protosulphate of iron and acid. - Lake Price.

When the negative has been assisted, in an inefficient exposure, by the addition of drops of nitrate bath to the developer, the peculiar " bloom " of high actinic quality will not appear when examined by diffused light; in its place darker tones and more opaque deposit of a blue or black character are seen. They are less satisfactory, being deficient in the truth and delicacy of gradation possessed by the former, and are apt to be very deceptive when printed; dark and vigorous - looking negatives occasionally allowing the light to permeate through their texture, whereas the most translucent of these, impressed under favorable actinic conditions, have a great power of resisting it, although their weak-looking, light-brown deposit would appear ill adapted to do so. - Lake Price.

154. The best printing qualities for a negative to possess are the following: The high - lights in the picture, that is to say, the most intense portions of the deposit, should allow the flame of a candle to be just seen through when held behind them; if of too great an opacity to admit of its being perceived at all, the resulting positives will probably be chalky and bare in the lights, and deficient in half-tones. Very small portions, representing actual white, should be of absolute opacity. There should be a general deposit of silver, with considerable variations of intensity over the whole surface, with the exception of the most vigorous darks, and in them it should approach very nearly to the bare glass, but only in small portions; if in large masses, it would denote under-exposure. Held up to the light, their color should be of a warm inky brown; when the plate is held horizontally over a dark ground, and viewed by diffused light, the appearance which especially distinguishes the deposit on the film in all negatives of the highest capabilities is a warm drab color, technically termed off the residue into a separate vessel, to settle before using again. Keep the plate in a horizontal position until the vsrnish be nearly set, and then stand it upon nails driven into the wall or upon a rack to dry. See 148.

The Manipulations.

155.Retouching The Negative - After the negative is varnished, it must be retouched. This is done by means of lead-pencils of various grades, which are so worked by hand or machinery as to improve the printing qnalities and the appearance of the model, too. The greatest care should be excercised by the retoucher not to alter the likeness or overdo me thing. The roughness of the skin ,freckles, and blemishes need to be obliterated, but the half - tone in the negative must also be carefully and judiciously preserved, lest all the charm of the picture be gone.

156. For this work a retouching - frame or desk is needed; a few of Faber's black lead - pencils; black - lead powder; India ink: a few sable hair - brushes, and some stamps. There are various preparations also for giving a "tooth " to the varnished surface, which must be applied in order to make it take or "bite" the pencil. A rough proof from the negative should be before you to guide you. Ones knowing what is required, one can, by careful practice, become expert in a short time in this deli and important operation. This done, the negative is ready for the print

"bloom" in negatives developed by pyrogallic solution; in those by iron it is rather more silvery gray and metallic. Such negatives are sure to print well; all the objects represented by them will be rotund in appearance, because their forms are thoroughly delineated by delicate half-tints, and the extremes of light and dark, with all the intermediate tones, will be well expressed. Their effects will be bright and spirited, equally removed from the - vapid monotony of over - exposed negatives, which, deficient alike in both whites and blacks, lose the power of the scale and range of chiaro-oaeuro which the two extremes should give them, and, from the crude and misshapen forms of the under - exposed, which fail because wanting the softening beauty and drawing given by middle tints. - Lake Price.

155. Retouching the - negative bat grown somewhat unpopular from excess of look skill, but seems to me quite legitimate work. But that is not the kind of aid of which I am thinking. I have lately been examining some of the best plain photographic portraits I can find, and they seem to me to be, as the artist says, "out of keeping." At first sight they appear perfect, and all right, but they don't wear well. After a little study they grow weak, and, unlike good art, they do not reveal some fresh beauty every day. The likeness is there, but is thin and spectral. - Charles Akers.

156. Retouching, like any other good thing, is liable to abuse, and it is due to this abuse that the opposition to it has arisen. Unfortunately, in a great majority of cases, the retouching of a negative is intrusted to unskilled hands, - persons who have no idea of the drawing and modelling of a face, the artistic effect of the touch, or even the printing requirements of a negative. This Is all wrong. Retouching should only be done by an artist - I mean a person with artistic taste and ability (for all of the so - called artists do not possess these qualities). - N. H. Busey.