50 
POPULAR SCIENCE EEYIEVT. 
M. Faber. The value of the black lead exhibited mu.-.t very 
much exceed a thousand pounds sterling. 
With some of M. Alibert’s plumbago, and also serving as 
the footing for a group of stuffed animals, are exhibited the 
largest specimens ever seen of that singularly hard and rare 
mineral, nephrite, or jade. The principal stone weighs upwards 
of half a ton. As well might we expect to see a diamond 
weighing a pound as a precious stone of this magnitude ; but 
there it is before us in the nave of the building, not staring one 
in the face, but modestly retiring, and probably not noticed by 
one out of ten thousand persons who think they have seen all 
the remarkable things, and Avho actually have looked at the 
stuffed animals that partly conceal this treasure. As it lies in 
the case uncut, the value is estimated at about £1,600 sterling. 
Other wonderful specimens of polished pictra dura are adjacent, 
cut into vases and columns, little remarkable for their form, but 
of the most extreme hardness. These articles are among the 
most characteristic of the Russian and Swedish manufactures 
in stone. 
3. Manufactured Minerals . — Of other stones, valuable for 
their great beauty, and worked into decorative shapes, there 
are many specimens. The rich dark green and red serpentines 
of the Lizard, in Cornwall, are the most striking and numerous 
articles of this kind exhibited. Some are very good, but in many 
of them an absence of good taste must be remarked, for an 
attempt has been made to use them for purposes for which 
they are not adapted. Very beautiful in places, these stones 
abound in flaws and weak white parts. Thus a large flat surface 
is generally a failure, while smaller and worked surfaces conceal 
or avoid the flaw.* Except the black marble of Derbyshire, 
there is no more beautiful or costly marble in the British 
islands, and few finer in Europe, than this serpentine ; and, 
although there are many objects constructed of it in bacl taste, 
there is a decided improvement in taste and style of manufac- 
ture when comparison is made with 1851. 
With much that is beautiful in marble manufacture, there is 
much that is weak, and much that is positively bad, nor is the 
bad taste confined to our own countrymen. In all these 
matters progress is desirable, and nothing can promote it more 
than the means of comparison afforded by a grand exhibition 
open to the whole world. With the good taste in style 
generally observable in Italian works of art, there is an adapta- 
tion of material to its object which cannot be too carefully 
* This variety of serpentine requires to be treated almost like agates for 
cameos. The places and colours of the flaws should be studied and converted 
into beauties. 
