JjJ HefearcJ^es refpeSl'mg the Covipojitton of EnameJ, 



Violet. 



Black calx of manganefe, employed with faline flaxes, 

 gives a very beautiful violet. By varying the fluxes, the fhade 

 of the colour may alfo be varied : it is very fixed as long as 

 it retains its oxygen. The oxyd of manganefe may produce 

 different colours; but for that purpofe it will be necelfary 

 that we (liould be able to fix its oxygen in it in diflerent pro- 

 portions. How to cffciSl this, as far as I know^ has never 

 yet been difcovcred. 



Thefe are all the colours obtained from metals. From 

 this it is evident that fomething Hill remains to be difcovered. 

 AVe do not know what might be produced by the oxyds of 

 platina, tungften, molybdena, and nickel : all thefe oxyds 

 are ftill to be tried; each of them muft produce a colour, 

 and perhaps red, which is obtained neither direftlv nor with 

 facility from any of the metallic fubllances formerly known 

 and hitherto employed. 



GENERAL REMARKS. 



Thofe who paint on enamel, on earthen-ware, porcelain, 

 &c. muft regulate the fulibility of the colours by the'moft 

 tender of thofe employed, as for example, the purple. When 

 the degree which is beft fuited to purple has been found, the 

 other lefs fufiblc colours may be fo regulated, (by additions of 

 flux,) when it is necelfary to fufe all the colours at the fame 

 lime, arid at the fame degree of heat. 



You may paint alfo in enamel without flux; but all the 

 colours do not e(|ually Hand the heat which muft be cm- 

 ployed. If the enamel, however, on which you paint be 

 very fufible, they may all penetrate it. This manner of 

 painting gives no thicknefs of colour; on the contrary, the 

 colours fink into the enamel at the places where the tints 

 are ftrongcft. To make them penetrate, and give thcrn 

 Kiftre, a pretty ilrong fire will be necelfary to foften the 

 tnamel and bring it to a ftate of fufion. This method can- 

 hot be praftifed but on enamel compofed with fand, v.hich 

 I call enamel fand, as already mentioned. It may be readily 

 , feen, alfo. that the colours and enamel capable of enduring 

 8 the 



