supporter of the American colonists in their dispute with the mother country. The visit of Edmund Burke to Bristol in 1774, and his election as member for the city, may be regarded as the climax of his career. Then it was that the famous tea-set was presented by Champion and his wife to Mrs. Burke, as a pignus amicitiæ. Still more elaborately decorated was the other service that Burke gave to Mrs. Smith, the wife of the friend of Champion, at whose house he stayed on this occasion. The shapes and the decoration of this service were founded on Dresden models, and the wreaths of laurels that formed an essential part of the design afforded a good field for the display of the green colour in which Champion excelled.

But Champion’s troubles were now to begin. In 1775 his petition to Parliament for a renewal of his patent was vigorously opposed by Wedgwood. Champion must have been put to great expense—he exhibited before a committee of the House some selected specimens of his porcelain. He, however, won his case, though the monopoly in the employment of the Cornish clays was restricted to their use as a material for transparent wares, a point of some importance to the Staffordshire potter. But meantime the American War was ruining his business—for Champion was in the first place a merchant trading with the West Indies and America—and it is probable that little porcelain was made by him after 1777. The next year Wedgwood, his inveterate opponent, in a letter to Bentley, says of him, ‘Poor Champion, you may have heard, is quite demolished.... I suppose we might buy some Growan-stone and Growan-clay now upon easy terms.’ In 1781, after a long negotiation, he disposed of his patent to some Staffordshire potters, and shortly after this he emigrated to America. Champion was only forty-eight years old when, in 1791, he died at his new home in South Carolina.

As Professor Church has pointed out, the paste of the Bristol porcelain is of exceptional hardness. It is, in fact, in some specimens as hard as quartz, that is, say, the hardness is equal to 7 in the scale of the mineralogist: the hardness of Oriental porcelain, it will be remembered, varies between 6 and 6·5; the glaze on the Bristol china is about 6 on the same scale. The fractured surface may be described as subconchoidal and somewhat flaky, with a greasy to vitreous lustre. On the Plymouth and Bristol wares, especially on the larger vases, may often be seen, when viewed in a favourable light, certain spiral ridges, the result of the unequal pressure of the ‘thrower’s’ hand. Similar ridges may indeed be observed at times on other hard paste wares, both Chinese and European, and this ‘wreathing’ or vissage, as Brongniart long ago pointed out, is the result of the too great plasticity of the clay,—a clay may, in fact, be too ‘fat’ to work well on the wheel. This plasticity, however, would be of advantage to the modeller, especially when working on a very small scale; indeed the delicate floral reliefs in biscuit, on the plaques we have already spoken of, could only have been made from a fine and unctuous clay. How refractory to heat this same paste is, was well proved by the fire at the Alexandra Palace in 1873, when so many fine specimens of English porcelain were destroyed. A biscuit plaque or medallion of Bristol porcelain passed uninjured (by heat at least) through this fire, while the soft porcelain alongside of it was completely melted.

The paste, then, of this Bristol ware is remarkable both for its resistance to heat and for its great plasticity. These are both qualities that point to an excess of kaolin in its composition, and this excess is confirmed by analysis. Professor Church found in a specimen of Bristol china 63 per cent. of silica, 33 per cent. of alumina, and only 4 per cent. of lime and alkalis. The percentage of alumina is about the same as that in the hard pastes of Meissen and of Sèvres, but the small amount of the other bases is quite exceptional. A paste of this composition would contain about 65 per cent. of kaolin.

And here, before ending, we may for a moment return to what is, perhaps, the crucial point of all in the composition of true porcelain—for it is one that has a radical influence both on the technical and on the artistic side. The first question we must ask when inquiring into the composition of any specimen of porcelain is this—What proportion of kaolin enters into its composition? Or if it is a matter of the primary constituents of the paste—What is the percentage of alumina that it contains? Now we may consider the composition of kaolin, after removing the water, to be silica 54 per cent. and alumina 46 per cent., and the nearer the composition of our porcelain approaches to these figures, the greater will be its hardness, its resistance to fire, and the greater also the plasticity of the paste—the greater in fact will be what we have called the ‘severity’ of the type.[255]

Now for the other component of porcelain, the petuntse or china-stone. The composition of this material differs widely, but let us take the mean of some analyses of Cornish stone. On this basis we may take silica 72 per cent., alumina 18 per cent., other bases 10 per cent., as our type. The result of adding such a material to our kaolin will be to increase the percentage of silica and of the ‘other bases,’ and to diminish the percentage of alumina in the resultant mixture. Our paste now becomes less plastic and the resultant porcelain more readily softened by heat, but at the same time less hard.

So far every one would be agreed. But the question now arises, are we to attribute this increased fusibility to the higher percentage of the other bases (these are, in the case of European porcelain, practically lime and potash), or in a measure at least to the increased amount of silica in the paste? We have here three variants, the silica, the alumina, and the ‘other bases,’ and the case is therefore somewhat complicated. I think, however, that the careful examination of any table giving the composition of various types of porcelain would show that up to a certain point an increase in the amount of silica promotes a lower softening-point in the paste, and this in cases where there is no important change in the proportion of the ‘other bases.’ I will illustrate this by comparing the composition of the severe hard paste of Sèvres on the one hand with an analysis of a mild type of Chinese porcelain on the other:—

Sèvres hard paste (1843).Chinese porcelain.
Silica,58per cent.70·5per cent.
Alumina,34·5”21”
Other bases,7·5”7·5”

No doubt, if the percentage of silica is further increased, say beyond 78 or 80 per cent., we get again a practically infusible body. But with a paste of this composition the resultant ware is no longer translucent—we pass from the region of porcelain to a true stoneware.

Thus we see that in composition a mild porcelain forms a middle term between stoneware on the one hand, and a severe porcelain on the other. In other words, stoneware cannot be regarded as an extreme type of a refractory porcelain.