32 THE ART OF PROJECTING. 



monium chloride, cupric sulphate, etc., and making a 

 rather dilute solution of them, and then adding a little 

 dissolved gum arabic. Flow the solution over the 

 plate, and let it remain horizontal until it is dry. The 

 crystals will be seen to have separated from the gum, 

 which will fill up all the intermediate space. Put over 

 the etching dish as before. The crystals will quickly 

 dissolve, and their outlines will be beautifully etched 

 upon the glass, which may now be washed clean in 

 water. 



7. Engravings may be transferred to glass by first 

 coating the glass with dammar varnish, or with Canada 

 balsam, and letting it dry until it is very sticky, which 

 will take half a day or more. The picture to be trans- 

 ferred should be well soaked in soft water, and care- 

 fully laid upon the prepared glass, and pressed upon it, 

 so that no air bubbles or drops of water are seen un- 

 derneath. This should dry a whole day before it is 

 touched ; then with the wetted finger, begin to rub off 

 the paper at the back. If this be skillfully done, 

 almost the whole of the paper can be removed, leaving 

 simply the ink upon the varnish. When the paper has 

 been removed, another coat of varnish will serve to 

 make the whole more transparent. 



8. A piece of glass may be smoked in the ordinary 

 way, and a design marked upon it. This makes a very 

 good and plain picture. If the design is needed for 

 keeping, heat some alcohol in a cup or small porcelain 

 dish, and hold the smoked side of the glass in the alco- 

 hol vapor for a minute or two, and afterward it may be 

 varnished with photographers' varnish, carefully flowing 

 it over the plate in the same way that plates are flowed 

 for photographic purposes. 



