end the different Methods of preparing it. 283 



the fame proportions of the two metals, and the tartar not 

 being always employed, as Paffcri has faid ; but the incon- 

 venience might eafily be prevented, if the workmen who 

 prepare Naples yellow would work according to a fample, as 

 is the cafe in regard to final t ; and if the different qualities 

 were in the like manner marked by numbers or characters. 

 Fougeroux was informed, from Naples, that there was an old 

 man ftill living there who prepared this yellow, but that he 

 kept his art fiich a profound fecret that it was apprehended 

 it would die with him. Nothing more of it was known 

 than that he expofed the metals which he employed to the 

 heat of a potter's furnace for twenty-four hours. 



Thofe who attempt to prepare this colour in Germany will 

 not certainly fet the fame value on the Italian receipt, 

 and that given by Fougeroux; for the diaphoretic antimony, 

 as well as white lead, are too dear — and fal ammoniac, which 

 is not cheap, is loft in the procefs. On the other hand, 

 fome advantage might be gained, if, according to the Italian 

 method, both the metals, with a fmall addition of an alkaline 

 fait, were reduced to the ftate of oxyds in an earthen-ware 

 furnace. But our enamel painters prepare a yellow glazing 

 not very different from the real Naples yellow, and for which 

 I find a receipt in a new work*, the author of which 

 feems to be a man of experience, but not of learning. Ac- 

 cording to this prefcription, one pound of antimony, fix 

 ounces of red lead, and two ounces of white fand, are 

 to be fufed together. The produce, which appears quite 

 black, is to be pounded, and then fufed again ; and this pro- 

 cefs is to be repeated till the whole mafs becomes thoroughly 

 yellow. Haifa pound of this mafs is to be mixed with two 

 ounces of red lead, and afterwards fufed ; and by this tedious 

 procefs an orange-yellow pigment will be obtained, which, 

 however, might be obtained with more eafc and certainty by 

 the method pointed out above. 



• Vollig eotdeftes gehcimnifs dcr kunflc fayencc, Englifchcs fteingut, 

 upd porzcllan zu machm. Leipzig, 1793, 8vo, p. 54- 



All 



