LOCAL DEVELOPMENT WITH GLITEEINE.
It sometimes happens that in spite of all the care bestowed upon the preparation of the negative, and the proper shielding of the various parts, the image is inclined to develop up too darkly in certain parts before the requisite amount of detail has been secured beneath, the denser portions. In such cases local development with glycerine is of great service. This is an exceedingly simple operation. The prints should be supported on a glass, and the shadows painted over with glycerine. Three measures or cups are then filled as follows : No. 1 with a strong developer ; No. 2 with a weaker developer, together with an equal quantity of glycerine ; and No. 3 with a very dilute developer, with glycerine. The strong developer is painted over the portions which are likely to be too light, and then the other parts are rapidly mopped or brushed over with the diluted solutions in proportion to their intensity. Care should be taken to blend the patches together, to prevent any chance of a line appearing ; although there is not very much fear of this, as the solutions are inclined to spread of their own accord and soon catch up to each other. A rough print should be at hand as a guide during the development, and the operator should make up his mind' exactly as to what he in tends to do, and the effect to be produced, before starting. Development should be
stopped the instant the required detail is out in the high lights. This method of pro cedure, carefully carried out, places a very effective control in the hands of the opera tor. It is even possible,. where the back ground is light, to vignette a print in this way. It must be understood, however, that the method is less valuable in the ease of small prints. Pictures smaller than whole-plate can seldom be treated very successfully, whereas prints 15 in. by 12 in. and over can be doctored to a considerable extent. The process is not greatly used in commercial work, for where extreme care is taken in shading up and preparing the negative, it is only seldom that occa sion arises for its use. Other acids besides hydrochloric have been suggested for fixing ; but the hydrochloric acid, if pure, is far superior to either acetic. sulphuric, or nitric. Prints should always be fixed face downwards, as this prevents the iron sinking into the paper.