Put this into a bottle, and when the crystals are dissolved, it is ready for use. It should be kept filtered, and can be used only once. Now in another bottle put Water 4 ounces. Nitrate of silver 48 grains. Remarks.--The impression is to be well washed after the developing solution has been poured off, and then the _re-developing solution_ (that portion containing the protosulphate of iron) can be poured on--the plate being held perfectly level: the surface is completely covered; the water containing the nitrate of silver should then be poured _rapidly_ on, to mix with the iron, when the surface of the impression will instantly commence to blacken; and if the action be allowed to continue for a lengthened period, say one minute, the impression will be ruined. It is a matter worthy of notice, that there is no perceptible action when the iron solution is poured over the glass; but the action is very energetic the instant the nitrate of silver solution comes in contact with the iron salt and the silver. As soon as any change can be observed, after the re-developer has been poured over the plate, it should be _quickly_ and copiously washed off with clean water, and then it is ready for the fixing process. I would dissuade novices in the art from practising with the _re-developing solution_, until they have first thoroughly mastered the entire process of taking negatives. The developing solution is the only one used by operators generally, and will, with proper care, produce satisfactory results. Fixing the Image. Water 8 ounces. Hyposulphite of soda 4 ounces. Remarks.--This is nearly a saturated solution. The glass can be put in a dish and the solution poured over, or held in the hand, in the same way as the plate in the daguerreotype process. It can readily be seen when a sufficient action has been attained, as the unaltered bromo-iodide of silver will be dissolved, leaving only the reduced surface holding the image. This action should not be continued too long, as it affects the intensity of the picture, injuring it for printing. The glass should be well washed by pouring over it clean water, and then it can be stood away to dry, in a _nearly_ perpendicular position, on clean blotting paper, or otherwise, as is most convenient; when thoroughly dry, it is ready for the finishing. Finishing the Image. This is done with the same material, and in the same manner, as that given for positives--page 134. Remarks.--The glass negatives, when not wanted for use, should be carefully put aside in a box, and kept free from dust and dampness: by so doing, it is believed that they will remain good for any length of time. Nitrate of Silver Bath.