104 ESSAY V. 



especially for painting upon porcelain, it will be of great use, 

 since, according to my information, the mine will yield a 

 sufficiently large quantity. 



It is to be observed of every species of manganese, that 

 the colour is the deeper the more violently it is roasted or 

 calcined. Hence that which is used for enamel or glazing 

 should be exposed for a long time to a strong heat. 



