120 
THE PRINCIPAL FLOOR. 
CERAMIC AND VITREOUS SERIES. 
A large collection illustrating the ceramic and vitreous manu- 
factures, especially rich in illustrations of the history of British 
Pottery and Porcelain, is exhibited at the southern or Jermyn 
Street end of the Principal Floor, where it is entirely separated 
from the mineralogical and metallurgical collections. The 
ceramic and vitreous collection is arranged partly in a series of 
forty-four Wall Cases distinguished by Roman numerals, partly 
in Glass Cases which rest on the cornice of the balustrade on 
each side of the staircase leading from the Hall, and partly also 
in several Pedestal Cases in the neighbouring area. It is not 
considered necessary to do more than give a very brief descrip- 
tion of the Collection of Pottery and Porcelain, since the subject 
is treated in detail in the Handbook specially devoted to this 
Department. 
It will be desirable to commence the study of the ceramic 
series by noticing the raw materials used in the manufacture. 
Examples of these materials will be found in the lower compart- 
ment of the Pedestal Case No. 53 and a valuable series of British 
clays, collected and presented by Mr. George Maw is exhibited 
in the lower divisions of the several Pedestal Cases (Nos. 52, 53, 
56, 62, 63, 64) occupying the two embayments. 
Clay , the plastic material upon which all ceramic manufacture 
depends, is essentially a hydrous silicate of aluminium, its 
peculiar fictile properties being generally regarded as due to the 
presence of the combined water. 
The clays exhibited include specimens of China clay, Cornish 
clay, or kaolin ; Bovey clay from Devonshire, and Poole clay 
from Dorsetshire. The other raw materials comprise samples of 
China stone and of flint ; the former is a granitic rock having its 
felspar only partially decomposed and retaining much of its 
alkaline silicate. 
A small series in the lower part of Case No. 53 illustrates 
the manufacture of pottery, but it is contemplated to replace 
these specimens, which are now antiquated, by a more modern 
series. A description of the processes of manufacture will be 
found in the Pottery Handbook. 
Case No. 63 on the western side, contains a miscellaneous 
series collected for the purpose of illustrating different kinds of 
glazing. It commences with certain glazed bricks from Assyria 
and Babylonia, and with the well-known blue-glazed frits of 
Egypt, such as the small turquoise -blue sepulchral figures, glazed 
with a silicate of sodium and copper. The use of white enamel, 
or a glaze rendered opaque by means of binoxide of tin, or stan- 
nic oxide, is illustrated by certain tiles from the AJhambra, 
several dishes of majolica ware, a sample representing Palissy’s 
rustic ware, and some specimens of Delft : in all these examples 
the brilliant white ground is obtained by the use of a stan- 
niferous glaze. Felspathic glazes are represented by many pieces 
of oriental porcelain, including some tiles from the Porcelain 
Tower at Nankin assigned to the year 1411. Salt glaze is 
