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434 THE PHOTOGRAPHIC NEWS. [JULY 13, 1883. cess. The free bichromate is soaked out, and, when dry, the print is exposed to a temperature of about 140° Centigrade, in order to harden the coating. When once more moistened, the print is ready for inking. This ink ing is best effected by the velvet roller, and it will be found that the ink adheres only to the exposed lines. When the transfer is properly inked, it is laid down on a carefully surfaced and cleaned zinc plate, and contact is established by means of the lithographic press. The back of the ad herent transfer being now moistened, it becomes easy to strip off the paper, leaving the fatty image fast on the zinc plate. In a series of articles which commenced on page 673 of our last volume, we detailed with some minuteness the steps which are necessary to etch the zinc into a i typographic block; but we may refer in this place to the leading features of the operation. The zinc plate is gummed, wiped, and inked with the usual lithographic roller, after which the plate is dried. Asphalt powder or | resin powder is now dusted over, and this material serves to add solidity and strength to the lines. Dilute nitric acid, about one to forty, is now allowed to act for a sufficient time to leave the lines in slight relief. A moderate heat now serves to so far melt the mixture of ink and resin as to cause it to flow down and cover the sides of the lines now standing in relief, after which the inking and the etching are repeated. By proceeding in this way each line ultimately forms the apex of a stepped ridge, and the printing block is finished. LENSES FOR INSTANTANEOUS WORK. A DISCUSSION has been going on for some weeks at the meetings of the Photographic Club on the general subject ■ of lenses for landscape work, and lately, particularly on those best adapted for instantaneous work. As we hinted in our last issue, there has been much re-threshing of thrice- threshed straw and stubble. Nevertheless, one point has been taken up generally, the importance of which we think is great. This is a con sideration of the angle of view which it is desirable to include iu a picture, apart entirely from the nature of the lens to be used. Of course, an angle of view cannot be laid down for all subjects; but at the same time it is true ! that there has been at all times since photography first came into existence what might be entitled a “ fashionable” angle; that is to say, one which photographers appeared to strive to use under most circumstances. Moreover, if no angle can be specified to serve for all cases, a desirable