172 W. C?*ookes on the Wax-paper Photographic Process. 



42. In the following bath, I have endeavored so to adjust the 

 proportion of nitrate of silver, as to avoid as much as possible 

 both the inconveniences mentioned above, 



Nitrate of silver .... 300 grains. 



Glacial acetic acid ... 2 drachms. 



Distilled water .... 20 ounces. 

 The nitrate of silver and acetic acid are to be added to the water, 

 and when dissolved, filtered into a clean dish (10), taking care 

 that the bottom of the dish be flat, and that the liquid cover it 

 to the depth of at least half an inch all over ; by the side of this, 

 two similar dishes must be placed, each containing distilled 

 water. 



43. A sheet of iodized paper is to be taken by one end, and 

 gradually lowered, the marked side downwards, on to the exci- 

 ting solution, taking care that no liquid gets on to the back, and 

 no air bubbles are enclosed. 



It will be necessary for the sheet to remain on this bath from 

 five to ten minutes ; but it can generally be known when the 

 operation is completed by the change in appearance, the pink 

 color entirely disappearing, and the sheet assuming a pure homo- 

 geneous straw color. When this is the case, one corner of it 

 must be raised up by the platinum spatula, lifted out of the dish 

 with rather a quick movement, allowed to drain for about half a 

 minute, and then floated on the surface of the water in the second 

 dish, while another iodized sheet is placed on the nitrate of silver 

 solution ; when this has remained on for a sufficient time, it 

 must be in like manner transferred to the dish of distilled water, 

 having removed the previous sheet to the next dish. 



44. A third iodized sheet can now be excited, and when this 

 is completed, the one first excited must be rubbed perfectly dry 

 between folds of clean blotting paper (14), wrapped up in clean 

 paper, and preserved in a portfolio until required for use ; and 

 the others can be transferred a dish forward, as before, taking 

 care that each sheet be washed twice in distilled water, and that 

 at every fourth sheet the dishes of washing water be emptied, 

 and replenished with clean distilled water ; this water should not 

 be thrown away, but preserved in a bottle for a subsequent 

 operation (49). 



45. The above quantity of the exciting bath, will be found 

 quite enough to excite about fifty sheets of the size here em- 



Eloyed, or 3000 square inches of paper. After the bulk has 

 een exhausted for this purpose, it should be kept, like the 

 washing waters, for the subsequent operation of developing (49). 



Of course these sensitive sheets must be kept in perfect dark- 

 ness. Generally, sufficient attention is not paid to this point. 

 It should be borne in mind, that an amount of white light, quite 

 harmless if the paper were only exposed to its action for a few 



