290 Manipulation in the Calotype process. [No. 4. 



In cool weather, and when no trace of the picture is visible on 

 the paper, I use equal parts of the acito- nitrate and gallic acid as in 

 the' normal solution. 



As the weather gets warmer or the picture appears more or less 

 on the paper, I decrease the quantity of aceto-nitrate, substituting 

 the gallic acid. This developing solution is laid on exactly as in 

 exciting with a clean cotton brush, the paper being kept wet until 

 the development is complete, and the minutest detail visible. Then 

 unpin the paper and wash in a couple of waters in a dish, after 

 which it may be put into the hypo-sulphate of soda solution (1 oz. 

 to 6 oz. of clean water) and taken into the light. When the picture 

 has lost all trace of the yellow iodide of silver it is fixed and must 

 be immediately washed in many waters for several hours, dried, and 

 finally waxed for the printing process. 



Let me add a few cautions to beginners. In iodizing, be careful 

 that the fingers are free from nitrate of silver stains ; I have spoiled 

 a whole batch of papers by neglecting this. 



See that not a trace of daylight is admitted into the opera- 

 ting-room, the single . candle even must be shaded, the light 

 may be allowed to come through the window however, if guarded 

 by a double fold of American sheeting dyed with the wood of the 

 jack-tree. 



Should the paper turn brown in spite of all precautions, be 

 assured the glacial acetic acid is too weak ; therefore increase the 

 quantity. 



Carefully wash out all the vessels used, more especially those in 

 which the gallo-nitrate has been mixed. 



Keep the hypo-sulphate of soda at a distance from all the other 

 chemicals, and set separate dishes aside for its use, two solutions will 

 serve to fix many proofs if filtered before use, even after it has. 

 become quite black. 



A clean flock of cotton-wool must be used for each picture, and 

 for each purpose in the Buckle brush. 



I think that the above reduces the calotype process to a simpli- 

 city, which can hardly be exceeded : it is also an exceedingly econo- 

 mical one, a matter of no small importance in India, where chemicals 

 are often not to be had, and are sold at such extravagant prices. 



