THE BOOK OF THE LANTERN. 103 



The varnish is simply flowed over the glass and allowed 

 to dry cold, which it will do in a very few minutes. 

 After it is thoroughly hardened it can be drawn upon 

 with a pencil in the way described, and can then be 

 coloured with water colours tempered with ox-gall, as 

 pointed out. We can now make the picture transparent by 

 the addition of another varnish, which must be of such a 

 composition that it will not dissolve or in any way act upon 

 the surface already laid upon the glass. Such a varnish 

 would be represented by one not containing benzine as a 

 solvent for its gums. I have not tried this method myself, 

 and so cannot speak from experience ; but I do not see any 

 reason why it should not succeed. 



