PHOTOGRAPHIC PROCESSES. 83 



the door, and by red light only take off the cover ; 

 give it a good stirring with a glass rod and replace 

 the cover. To tell when the silver is all formed into 

 bromide of silver, take a small piece of the jelly to 

 the light and cut it in two; if it is all alike, the 

 action has taken place, if it is not the same colour all 

 the way through, there is still free silver present. 

 Do not put the piece back into the pitcher, as it 

 would fog the balance. When the silver has all been 

 formed into bromide of silver, the emulsion could be 

 washed, melted, and plates prepared, but they would 

 be slow. Now leave the emulsion standing in this 

 brine of bromide of ammonium, &c., from one to five 

 days or more, according to rapidity you want. Three 

 days makes a rapid plate, five to six days makes a 

 very rapid plate. The reason of this is the excess of 

 bromide of ammonium partially dissolves the bromide 

 of silver. The longer it remains in the brine, the 

 finer it becomes ; also, the weaker the brine, the finer 

 the bromide of silver. But by making it weaker 

 than is recommended here takes too long for the 

 bromide of silver to form. 



To WASH THE EMULSION. 



Let the water run through the tube to bottom of 

 pitcher and off at faucet below. To tell when the 

 emulsion is sufficiently washed, take some of the 

 waste water running from the faucet into a two- 

 ounce bottle and add a few drops of silver solution ; 

 there will be a precipitate of bromide of silver. In 



a2 



