27Q JReceipls for Enamel Colours, 



Flux, No. 2 I 



Flux, No. 6 •2|- 



Grind in water for use. 



Greens in painting on enamel, are formed of various shades 

 by mixing blue and yellow, or blue and orange, S:c. in different 

 proportions. 



Blue. 

 Take of black oxide of cobalt . . 4 

 Flint powder . . . . . . [) 



Nitre 13 



Mix them well in an earthenware mortar, and heat them in 



the crucible, in a strong fire of coke and charcoal, till perfectly 



melted* J then pound the mass, wash it in cold water, and dry it. 



Of this take . . . . 1 



Flux, No. 5 .... 1 



Grind in water for use. 



Another Blue. 

 Take black oxide of cobalt . , 1 



Raw borax . . , , . , 1 



Melt them together. 



Of this mixture take . . . . 2 



Blue pot-metal glass .. ..10 



Red lead | 



Melt them in a very strong fire. If either blue is too soft, add 

 a little royal smalt : if too hard, a little flux made of blue glass 2, 

 borax 1. 



Piirple. 

 Take fine-grained gold from the refiners, and dissolve it to sa- 

 turation in an aqua regia made of strongest 

 Nitric acid . . 1 ~\ 



Muriatic acid . . 3 V by measure. 

 Distilled water . . 3 J 

 Make the solution in a clean Florence oil flask, placed on sand 

 near the fire. Pour melted tin into cold water, and take of the 

 clean parts of this tin . . . . . , . . . , 1 



Aqua regia, diluted with water in the same propor-H ^ 

 tion as above . . . . . . . . , .J 



Place the acid and the tin in a large bason covered with a 

 plate, in a temperate heat ; when the tin is all dissolved, add 

 Strong red fuming nitrous acid . . I 



Tin 1 



And instantly cover the bason with the plate, to prevent the 



* If these preparations are not sufficiently fluid in the melted state to 

 pour out of the crucible, the colour will stick to a piece of steel bar when 

 it is wai'in, and may be drawn out ; and sometimes the blues are made in 

 crucibles lined with flint powder as bel'ore mentioutd. 



fumes 



