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First process for biting in or engraving the plate. The following 

 solutions must be put in the capsulae, in sufficient quantity, so as to 

 entirely cover the plate: 1. Acidulated water. 2. Alkaline water. 

 3. Alcoholized potash, in covered capsulae 4. Caustic potash, in 

 covered capsulae. 5. Distilled water. 



The plate being put upon the glass holder or spoon, is plunged 

 in the acidulated water, and agitated during a few seconds, then 

 put into a glass funnel, and washed with distilled water. It is 

 taken again with the glass spoon, and plunged in the capsula con- 

 taining alcoholized potash. This capsula is covered with its glass 

 cover, and then heated, by means of a spirit-lamp, to about 144 

 Fahrenheit. The plate must remain in the capsula half an hour, 

 during which the solution is heated now and then, and agitated. 

 During that time, the following acid solution, which will be called 

 normal acid, must be prepared ; it is composed as follows : Water 

 600 parts, nitric acid 45 parts, solution of nitrite of potassa 12 parts, 

 solution of common salt 45 parts. These proportions are in volume. 

 The normal acid must be poured in a capsula, covered with its glass 

 cover, and a sufficient quantity must be kept in the bottle. 



When the plate has been immersed in the alcoholiz?d potash 

 during half an hour, it is taken out of the solution by means of the 

 glass holder, and immediately plunged in the alkaline water, and 

 agitated pretty strongly ; from thence it is put in distilled water. (A) 



This being done, the plate is plunged in the acidulated water, and 

 moved about therein for a few seconds: it is then put into the 

 normal acid. When the plate has been immersed a few seconds in 

 the acid, it is taken out by means of the glass holder, taking care to 

 keep it as much as possible covered with the solution, and it is im- 

 mediately placed horizontally upon a stand, and as much acid as the 

 plate can hold is poured upon it from the bottle ; it is then heated 

 with a spirit-lamp, but without attaining the boiling point. During 

 this operation it is better to stir or move about the acid on the plate 

 by pumping it, and ejecting it again, by means of a pipette or glass 

 syringe ; after two or three minutes the acid is thrown away, the 

 plate is put in the glass funnel, and there well washed with water, 

 and afterwards with distilled water. (B) 



Then, without letting the plate dry, it is put upon the fingers of 

 the left hand, and with the right hand some ammoniacal chloride of 

 silver, which is moved about the surface by balancing the hand, is 

 poured upon it ; the solution is renewed until the chloride, formed 

 by the action of the acid, is dissolved ; the plate is then washed by 

 pouring upon it a large quantity of ammoniacal water, and after- 

 wards some distilled water. (C) 



