t TRcfearches refpeSlivg the 



fufed with three part- of white glafs, (which contains ncithct 

 iead nor other metallic oxyds,) and one of glafs of borax, 

 with a half or fourth part of nitre; yet this calx, fo white 

 when mixed with the compofition of enamel, made with 

 enamel fand and the combined oxyd of lead and tin, inftead 

 of increafing, tarniihes the whitcnefs, and only gives a blueifli 

 enamel of a livid colour *. Perhaps enamels, completely 

 made and mixed together in the firft inftance, would not 

 produce the fame effeft; but this I never tried. I have, 

 however, employed this compofition as a flux for coloursj 

 which, applied afterwards on the enamel of earthen-ware, 

 preferved its beauty. I put fome of this pure enamel alfo 

 over that of earthen-ware, and I think it prcferved its 

 whitenefs. 



The principal quality of good enamel, and that which 

 renders it tit for being applied on baked earthen- ware, or on 

 metals, is the facility with which it acquires luftre by a mo- 

 derate heat, (a cherry-red heat, more or lefs, according to 

 the niiture of the enamel,) without entering into complete 

 fufionf. Enamels applied to earthen-ware and metals pof^ 

 fefs this quality. They do not enter into complete fiifion; 

 they aiTume only the ftate of pafte, but of a pafte exceedingly 

 fjnrf ; and vet when baked one might fay that they had b^en 

 completely fufed. 



There are two methods of painting on enamel : on raw 

 or on baked enamel. Both thefe mr.thods arc employed, or 

 may be employed, for the fame obje6l. Solid colours, ca.- 

 pable of fuftaining the fire neceflary for baking the enamel 

 ground, may be applied in the form of fufed enamel on that 

 which is raw, and the artift may afterwards finifli with the 

 tender colout-s. The colours applied on the raw material do 

 not require any flux ; there is one, even, to which filex muft 

 be added, that is, the calx of copper, which gives a very 



* Antimony, employed in any manner as a gazing for tanhen- ware, 

 woijld he more dangerous than lead ; even the latter fiiould, if poffible, 

 be dfcardtd. — Edit. 



+ The ingenious author has omitted another principal quality- It 

 oui!;ht never to contain fuch a portion of deliqutfciiig faits, as to rndanger 

 its hi\m afterwards mjared by water. This takes place oftener than is 

 generally fufpedlcd.— Edix. 



Ibt:autlfuj 



