THE POTTERS ART. 



can be taken out of the mould, which is caused by the absorbent 

 nature of the plaster of which the mould is composed, is equal to 

 a reduction of one inch and a half in the height. These casts are 

 then put together by the " figure-maker ; " the seams consequent 

 upon the marks caused by the subdivisions of the moulds being 

 carefully removed, the whole is worked upon to restore the cast to 

 the same degree of finish as the original model. The work is then 

 thoroughly dried, to be in a fit state for firing, since, if it were 

 put in the oven while damp, the sudden contraction consequent 

 upon the great degree of heat to which it would be suddenly 

 exposed, would be very liable to cause it to crack : in this process 

 it again suffers a further loss of one inch and a half by evapora- 

 tion, and it is now but twenty-one inches high. Again, in the 

 "firing" of the bisque oven, its most severe ordeal, it is dimi- 

 nished three inches, and is then but eighteen inches high, being 

 six inches or one-fourth less than the original. It loses, there- 

 fore, in the entire process, one-fourth of its linear, and therefore 

 more than one-half of its cubical dimensions. Nevertheless, such is 

 the consummate skill brought to bear on this beautiful manufacture, 

 that in good specimens there is not the slightest discoverable 

 distortion or defect of form or outline. 



The perfection to which this branch of the potter's art has 

 recently attained, is such as to render it probable that it will 

 eventually be to sculpture what engraving has been to painting, 

 but with a much closer affinity, identity of colour and texture 

 being attained, as well as that of outline and design. 



18. The enamel colours used in the ornamentation of porcelain 

 are produced by certain oxydes of the metals combined Avith other 

 substances, called fluxes, which have the effect of facilitating their 

 fusion. Thus the oxyde of gold produces tints of red, such as 

 crimson, rose-red, and purple. Reds are also produced by the 

 oxydes of iron and chrome. The same oxydes, as well as those of 

 cobalt and manganese, produce blacks and browns ; those of 

 uranium, chrome, antimony, and iron produce orange; those of 

 chrome, and copper, green ; and those of cobalt and zinc, blue. 

 The fluxes for these various oxydes are borax, Hint, oxyde of 

 lead, &c. 



These colouring materials are worked up with essential oils and 

 turpentine, and a very great disadvantage under which the artist 

 labours is, that the tints upon the palette are in most cases 

 different to those they assume when they have undergone the 

 necessary heat, which not only brings out the true colour, but also 

 by partially softening the glaze and the flux, causes the colour to 

 become fixed to the ware. This disadvantage will be imme- 

 diately apparent in the case where a peculiar delicacy of tint is 

 170 



