ENA 



ENG 



Concerning the J3lack$. 



Black colours are the most difficult to 

 be obtained very beautiful. There is no 

 metallic oxide, which, singly, affords a 

 fine black. Manganese gives the best ; 

 iron, an opaque, dull, blistered black, 

 which easily turns to red. The makers 

 of colours have therefore combined se- 

 veral metallic oxides, which, singly, do 

 not afford blacks, and they have obtained 

 a very beautiful colour, but it is subject 

 to scale and become dull. 



The oxides are, those of manganese, 

 the brown oxides of copper, and a little 

 of that of cobalt. Grey is obtained by 

 suppressing the quantity of copper and 

 increasing the quantity of flux. 



The Sevres manufactory is the only 

 one which has as yet produced beautiful 

 blacks with a strong fire. This is more 

 owing to the quality of the biscuit, than 

 to any peculiarity of process. It is by a 

 mixture of blue with the oxides of man- 

 ganese and iron that they make this very 

 brilliant black. 



The blacks for opaque glass are made 

 the same as for painting, by giving dif- 

 ferent doses of solvent. 



After the display of the principles of fa- 

 bricating each principal colour, it is clear, 

 that by mixing these colours all possible 

 shades may be obtained : and also that 

 care in the preparation, choice of mate- 

 rials, and just proportions of closes, must 

 exhibit very sensible differences to the 

 experienced eye of a painter. A know- 

 ledge of the composition of colours does 

 not give the requisite care and neatness 

 in making them up. 



On recapitulating the facts here just 

 stated, in order to present them in a ge- 

 neral view, we see, first, that amongst 

 the colours usually employed for hard 

 porcelain, one only is susceptible of 

 change, namely, the carmine : and this 

 may be replaced by the reds of iron, and 

 then no colour changes. 



M. Brougniart presented to the Insti- 

 tute an unbaked head made in this man- 

 ner, and a painting of two roses, the one 

 baked, and the other in its first state. 

 There was not any difference between 

 them. 



Secondly, That amongst the colours 

 of soft? porcelain and enamel, several 

 change considerably, particularly the 

 reds of iron and gold, with the yellows, 

 greens, and browns. None have been 

 substituted instead of them, this species 

 4>f painting being almost abandoned. 



Thirdly, That several of these colours 



change likewise upon the glass by be- 

 coming perfectly transparent, particular- 

 ly the yellows and violets. 



Fourthly, That neither an additional 

 calcination, nor an additional fusion, as 

 has been suspected, will prevent them 

 from changing : for this method alters 

 the colours that change, and does no- 

 thing to the rest. The change which se- 

 veral colours undergo on tender porce- 

 lain, and on glass, does not therefore re- 

 late to the nature of their composition, 

 but rather to that of the body on which 

 they are placed. Consequently, by sup- 

 pressing the carmine of gold from the- 

 colours of hard porcelain, we shall have 

 a series of unchangeable colours. 



ENARGEA, in botany, a genus of the 

 Hexandria Monogynia class and order. 

 Essential character : calyx none ; petals 

 six, oblong, ovate, concave, acute, three 

 outer, three inner, green spotted ; berry 

 three-celled, with four or five globular 

 seeds. There is but one species, viz. E. 

 marginata, a native of Terra Del Fuego. 



ENCALYPTA, in botany, a genus of 

 the Cryptogamia Musci class and order. 

 Capsule cylindrical ; fringe simple, of 

 sixteen linear erect distinct teeth ; veil 

 campanulate, inflated, lax. There are 

 six species. 



ENCAUSTIC, the same with enamel- 

 ling and enamel. See ENAMELLING. 



ENCAUSTIC painting, a method of paint- 

 ing made use of by the ancients, in which 

 wax was employed to give a gloss to 

 their colours, and to preserve them from 

 the injuries of the air. 



ENCHASING, or CHASING, the art of 

 enriching and beautifying gold, silver, 

 and other metal work, by some design, 

 or figures represented thereon, in low 

 relievo. See RELIEVO and SCULPTURE. 



Enchasing is practised only on hollow 

 thin works, as watch-cases, cane-heads, 

 tweezer-cases, or the like. It is per- 

 formed by punching or driving out the 

 metal, to form the figure from within 

 side, so as to stand out prominent from 

 the plane or surface of the metal. In 

 order to this they provide a number of 

 fine steel blocks, or puncheons, of divers 

 sizes ; and the design being drawn on 

 the surface of the metal, they apply the 

 inside upon the beads or tops of these 

 blocks, directly under the lines or parts 

 of the figures ; then with a fine hammer, 

 striking on the metal sustained by the 

 block, the metal yields, and the block 

 makes an indenture or cavity on the in- 

 side, corresponding to which 'there is a 



