60 
THE PRINCIPAL FLOOR. 
Some of the Chinese mirrors possess the very remarkable 
property of reflecting from their polished surface the figure 
which is wrought upon the back. The cause of this has been 
studied by Profs. Ayrton and Perry, who refer it to slight 
inequalities of superficial curvature, produced by the buckling 
of the bronze during manufacture. 
In this Case there is also exhibited a small collection of the 
principal alloys used by the Japanese in their art metal-work. 
These present a great range of colour, some of the tints being 
extremely beautiful. The use of peculiar pickling solutions 
developes the superficial stains and patina exhibited by certain 
of these alloys. 
A large number of analyses of oriental metal -work, including 
many Japanese alloys, in the South Kensington Museum, have 
been made under the direction of Prof. Roberts-Austen, and 
published by the Department of Science and Art (1892). For 
information on Japanese bronze casting, the visitor may refer to 
Mr. W. Gowland’s paper in the Journal of the Society of Arts, 
May 1895, p. 523. 
Art Applications of the Metals. Case No. 42. 
The objects grouped in this Case serve to show the characters 
of the metals in a pure and in a mixed state, and to illustrate 
their application to works of art and to art manufacture. 
Statuettes in tin and copper show the characters of the metals 
in their ordinary states. One in brass exhibits the result of 
combining copper and zinc, while those of Raphael and Michael 
Angelo are bronzes, in the proportion of 90 parts of copper and 
10 of tin. The statuette of Humboldt is of zinc, but it has been 
subsequently coated by the electro-chemical process. 
The silver and bronze vases are copied from antique specimens 
found in Pompeii, and now preserved in the Museum at Naples. 
Corinthian bronze, in which one of them is cast, consists of 
two-thirds copper and one-third silver. This composition is 
said to receive its name from its having been discovered by the 
accidental melting together of statues of copper and silver which 
were destroyed by fire at Corinth. Electrum was one of the 
celebrated mixed metals of the ancients, of which we have here 
an example. Our standard silver {see Silver Vase) has a com- 
position of 222 silver and 18 copper ; by the admixture of 
the latter metal the required hardness is obtained without 
interfering with the colour of the silver. 
Among the miscellaneous objects placed against the walls on 
this floor is a fine old Flemish Monumental Brass, near 
Case 42. This brass forms part of the mixed -metal series 
exhibited. It is of Lodewyc Cortewille, of Cortewille, near 
Liege, who died in 1504, and of his wife Colyne van Castre, 
who died 1496. The analysis made in this establishment shows 
its composition to be — Copper, 64*0 ; Zinc 29'5 ; Lead, 3 5 ; 
Tin, 3-0. 
