110 J. Waterhousc — The Ajypliccdion of Photography [No. 2, 



Nitrate of Silver, 1 part. 



Cyanide of Potassium, 10 „ 



Water,... 100 



The gelatine tissue attached to the copper plate is allowed to dry, 

 and then developed in warm water in the usual manner, great care being 

 taken not to loosen the lines, an accident which is very liable to happen, 

 though the preliminary drying of the tissue before development tends to 

 prevent it. 



When the image is quite clear from all soluble gelatine, the plate is 

 well drained and plunged into a bath containing — 



Tannin, 5 parts. 



Strong Spirit s-of- wine, ... 100 „ 



This at once removes all moisture from the gelatine relief, hardens it, and 

 gives it a fine grain, coarser in the shadows than in the lights. The plate 

 remains a few minutes in this bath till the action is complete in the deepest 

 shadows ; the tannin is then washed off with a little spirits-of-wine, and the 

 plate is allowed to dry. 



The gelatine relief has now to be prepared for receiving the electrotype 

 deposit. A band of copper having been soldered to it, the back of the plate 

 is coated with Brunswick black, to prevent deposition of the copper upon 

 it. When the backing is dry, the margins of the picture are cleaned with 

 a little of the silvering solution. The gelatine surface then receives a 

 very slight coating of wax dissolved in turpentine, which is well polished off, 

 and is rubbed over with fine plumbago or silver-bronze powder to render the 

 surface conducting. The plate is then ready to be placed in the depositing 

 bath. 



Any good electrotyping arrangement may be used, but I prefer a Smee's 

 battery with a separate depositing trough, containing a solution of 10 parts 

 each of sulphate of copper and sulphuric acid in 100 parts of water. 



A plate of copper, to serve as an anode and connected with the silver 

 plate of the batterj'-, is laid horizontally about an inch above the bottom of 

 the depositing trough which should be large enough to allow the plate 

 bearing the gelatine relief to be slipped under the anode. The relief -plate 

 is connected with the zinc plates of the battery and, when everything else 

 is ready, the circuit is completed by slipping it into the depositing trough 

 under the anode. By laying the plates horizontally in this manner the 

 deposit is more even and the gelatine film seems to be more readily covered 

 with copper. 



When the deposit of copper is of sufiicient thickness it is separated 

 from the matrix, and only requires a gentle ' oil-rubbing' to be fit for 

 printing. 



