O X Y 



of oxygen to i of muriatic acid. Thefe oxygenized 

 acids combine with the different bafes, and neutrahze them 

 but they are by no means permanent, readily g>v'ng "« 

 their fuperfluous oxygen upon the apphcation of heat, &c 

 The oxygenized muriatic acid alfo .s decompofed by the 

 oxyd of Vdver, chloride of filver is formed, and the oxygen 

 is fet at liberty. 



O X Y 



By fimilar methods, M. Thenard has been able to com- 

 bine additional dofes of oxygen with many of the metallic 

 oxyds. See Annales de Chimie et Phyfique, vols. viii. 



and ix. 



OXYMURIATIC Acid. See Chlorine. 



OXYPRUSSIC Acid. See Cyanogen and Prussic 

 Jcicl. 



P. 



Vol. XXVI. 



PACKERSFIELD, 1. 3, r. 1076. 

 PACOLET. Add— Alfo, a town of Rutland 

 county, in Vermont, containing 2233 inhabitants. 

 PADMA, 1. 2, dele of. 



PAINT, in Geography, a townihip of Fayette county, 

 in Ohio, having 534 perfons. — Alfo, a towntliip of High- 

 land county, in Ohio, with 775 inhabitants. 



PAINTING in Enamel. Of all the various mediums 

 of painting none is fo durable as enamel, fince time, which 

 deftroys all other things, alters neither its beauty nor its 

 brilliancy ; and that this great advantage may not be too 

 eafily attained, it may be faid, alfo, that no other method 

 of painting unites in itfclf fo many difficulties in the 

 execution. 



Enamel painting differs from every other kind of paint- 

 ing, in employing, as a vehicle for the colours, glafs or 

 fome vitreous body, to hold the parts together, and fix 

 them to the ground on which they are laid. This being 

 mixed with the colours, and fufed or melted by means of 

 heat, becomes fluid ; and having incorporated with the 

 colours, forms together with them a hard fhining mafs. 

 This vitreous body, called flux, is to an enamel pifture 

 what oil, gum, or varnifh, is in the other modes of painting, 

 as by its means the work acquires its full degree of brilliancy 

 and depth. See Flux. 



The quality of the flux is an objeft of the greatell con- 

 fideration to the enamel painter ; when it is eafily fufible, it 

 is called foft ; and when it requires a greater degree of heat, 

 it is called hard : thefe terms are applied as well to the 

 enamel grounds, and the other vitreous fubftances employed, 

 as to the fluxes. It is effential that the fluxes compounded 

 with the different colours fliould be of the fame degree of 

 hardnefs, or nearly fo ; as otherwife fome, from being too 

 foft, would be deftroyed by the fire ; while others, from 

 having the contrary defeft, would not be fixed to the plate, 

 nor acquire their proper colour. It is neceffary too, that the 

 plate or enamel ground on which the pifture is painted 

 ftould be harder than the colours ; for if they both melted 

 witli the fame degree of heat, they would neceffarily run 

 together, and render the work indiilinft. 



The ground-work of the enamel plate is metal. Gold 

 and copper are thofe chiefly employed. For fmall plates, 

 where great neatnefs and delicacy are neceflary, gold is 



preferable, on account of its not bliflering round the edges 

 in the fire, as is the cafe with copper : for large plates, 

 copper is preferred, not only on account of the difference 

 of expence between it and gold, but becaufe it is found 

 from experience to be better : gold being a much fofter 

 metal than copper, the plate, if of any fize, is not found 

 to retain its original form, in pafTing through the fire, fo 

 well, when made of it, as when it has copper for its bafis. 

 The form of the enamel plate is flightly convex ; if it were 

 made quite flat, in paffing through the fire repeatedly it 

 would become concave. It is on this account that gold is 

 not proper for large plates, being heavier as well as fofter 

 than copper : its own weight added to that of the enamel 

 would naturally tend, while in a ftate of fufion, to fink 

 them in the middle, and render the furface warped and un- 

 even, unlefs they experienced refiftance from the back, 

 which would mofl probably occafion the deftruftion of the 

 whole. 



When platinawas firft difcovered, it was imagined, from 

 its great difficulty of fufion, that it would be of effential 

 fervice in the making of enamel plates, but it was found to 

 be ufelefs for that purpofe : as, although a plate made of it 

 pafled through the fire with its form unaltered in the fiightefl 

 degree, there was found wanting that union between the 

 enamel and the metal on which it is laid, that is fo neceflary to 

 enfure its fafety, fince a flight fliock was fufiicient to fepa- 

 rate them and leave the platina quite free from the enamel. 

 With gold and copper it is quite different, it is hardly pof- 

 fible to free the gold entirely from the enamel, and fo rtrift 

 is its adhefion to the copper, that if broken it invariably 

 brings a lamen of the copper with it. The mode of pre- 

 paring the enamel plate for painting is exaftly fimilar to that 

 for watch and clock dialling (fee Enamelling), with this 

 exception, that over the enamel is paffed a fofter body, a 

 flux for the purpofe of incorporating with the colours laid 

 on : this flux fliould agree with every colour ufed. 



The colours ufed in enamel painting are all prepared from 

 metals, earths, or other mineral bodies, mixed and melted 

 with certain proportions of flux, which, when fufed, dif- 

 cover the colours, and fix them to the plate. The colours 

 of the enamel painter are few, and his palette, when com- 

 pared to that of other artiils, of the mofl difcouraging 

 defcription, many of them appearing very different before 

 and after paffing the fire. This is indeed one of his greatell 

 difficulties, and one which requires the greatell praftice to 



overcome. 



