TAKING PICTURES 133 



So the negative is placed in a solution of hypo, which is 

 called the fixing solution. This dissolves the silver salts 

 which have not been acted on. That which remains on the 

 plate is permanent and it may now be taken into the light. 



Developing in dark room. There are two methods of 

 developing, the dark-room method and the tank method, 

 which can be carried on in daylight. In the dark room all 

 ordinary light must be excluded, but it is found that red 

 light has very little effect on the plates, and so a red light is 

 provided by means of which the work can be done. The 

 developers are usually bought in the form of powders which 

 are dissolved in water and poured into a tray. Two other 

 trays, one with water and one with hypo, are provided. 



The plate is first immersed in water in one of the trays 

 and then placed in the tray containing the developer. In a 

 short time lights and shadows begin to appear, and then the 

 outline of the objects. The stage of development may be 

 watched by holding the plate up to the red light. Only 

 experience can tell one when to stop the development. The 

 plate is then placed in water to remove the excess of developer. 

 Then it is placed in hypo where it is allowed to stay till the 

 salts that have not been affected by the light are dissolved. 

 This takes about fifteen minutes. The plate is then washed 

 for about an hour in running water, or it may be left to soak 

 for five minutes each in five changes of water. The plate 

 is then taken out and dried. 



Films may be developed in the same way. They may be 

 cut and developed separately or the whole film may be 

 developed. 



The glass plates may be developed also in the dark room 

 in a tank in which a number of plates can be developed at 

 once. The developer is poured into the tank, and the plates 

 are put in and allowed to remain a certain length of time 

 according to the strength of the solution and its temperature. 

 When the time is up, the developer is poured out, the plates 



