224 iMPROTGMBNt IN fRE AQUATIlTTA PROCKtS. 



but this will depend on the state of the weather: for if H 

 thould be intensely hot, it ought to be left all night to har- 

 den. 

 hf"*'^ff^h"^* Now the varnish is presumed to be sufficiently hard, you 

 touches. may rub off the touches made with the foregoing described 



ink with spittle, and use your finder to rub them up; 

 should it not come off very freely, put your wa'ling-wax 

 tound the marf^in of your plnte, and then pour on the 

 touches some warm water, but care must be taken it is not 

 too hot. 



The touches now being clean taken off, wash the o'ate well 

 and clean f: cm all impurities and sediment of the ink, with 

 . co\d soft water; then dry the plate at a distance from the 

 fire, or else in the sun; and when dry, pour on your aqua 

 fortis, which should be in cold weather as follows: — 

 Acid. To one pint of nitrous acid, or strong aqua fortis, add two 



parts, or twice its quantity of soft water. 



In hot weather to one part of nitrous acid add three pafts 

 ^ of water. 



In every part of this process avoid hard or pump water. 

 Biting in. The last process of biting in with aqua fortis must be 



closely attended to, brushing off all the bubbles that arise 

 from the action of the «qiia fortis on the copper. 



In summer time it will take about twenty minutes to get 

 a sufificient colour: in winter perhaps half an hour, or more. 

 All this must depend on the state of the atmosphere and 

 temperature of your room. If any parts require to be stop- 

 Stopping out. p^H out, do the same with turpentine varnish and lamp-' 

 black, and with a camel-hair brush pass over those parts 

 you consider of sufficient depth ; distances and objects 

 receding from the sight of course ought not to be so deep as 

 your lore-grounds; accordingly you will obliterate them 

 with the foregoing varnish, and then let it dry, when you 

 will apply the aqua fortis a second time, and repeat thi» 

 just as often as you wish to procure different degrees of 

 colour. 



Every tirue you take off the aqua fortis the plate must be 

 wash* d twice with soft water, and then set to dry as* before. 

 To a'scenain To ascertain the depth for your work, you should rub a 

 Se work small part with a piece of rag dipped in turpentine, apd then 



apply 



