Basis. As a basis, employ a polished glass plate, three lines in thickness, or may be thicker. These plates are polished mat on one side by rubbing them with finely levigated emery powder; the powder is moistened with a little water, and applied to the glass surface, the emery being uniformly moistened by rubbing with the finger. This is very necessary, for should any dry emery come in contact with the glass, deep scratches are at once produced. Another glass plate is placed upon the one covered with moist emery, and the former is rubbed by a circular movement, and with very little pressure. In a few moments you perceive that the noise from the breaking up of the large particles ceases, and then more pressure, and freer and quicker manipulation may ensue. For about ten minutes the task should be continued, the grains of emery becoming smaller as the work proceeds, and the mat surface of a finer character. If, after the plate has been washed, it turns out that the glass surface has not been evenly rubbed, or that, by reason of the inequality of the plate, certain portions have not been touched, the grinding must be proceeded with, a fresh supply of emery being obtained. The action must be condouble film from the glass. The tray should be large, deep, and quite full of water; then in the operation of stripping the film will be turned over. Remove the glass from the water, leaving the film floating topsy-turvy; wash the strips off the edges, dip into clean, warm water, and flood with a thin, warm solution of gelatin. Rest one end of the glass on the edge of the tray, and the other on some support to keep it level. Now lift the film by the two nearest corners, and gently draw it out of the water on to the glass. It will easily slip over the gelatin without bubbles. Tilt the glass, keeping hold of the corners to prevent the film slipping off, and gradually raise it to let the surplus gelatin drain off. Any stray gelatin which has run over the surface can be removed by now washing, or after it has dried. The India-rubber solution can be made by dissolving thin sheet India - rubber (black) - such as tobacco pouches are sometimes made of - in benzine or benzoline. If the latter, see that it be free from paraffine, which would prevent the India-rubber from drying. The use of the coating of India-rubber is to prevent the coating of plain collodion from dissolving that containing the negative. A very thin coating therefore suffices. For large negatives, a second coating of India-rubber and collodion is advisable. Negatives so reversed have one single fault - the film is easily scratched. Great care is therefore necessary with these for our work. - George Smith.