No. 276 J 
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The enamel is made of petuntze and feldspar. Besides this, it is said 
that the pieces are sprinkled with a species of fine earth previous to 
their painting, which produces a wonderful effect in increasing and aug- 
menting the beauty of the surface, and which lessen also very much the 
labor of painting. 
4. Kaolin of Ficence, 
There is a beautiful earth at Schio, in the Vicentin, which is known 
in commerce under the name of ierre de Vicmce, It is a kaolin proceed- 
ing from the decomposition of pyritous felspathic rock. This earth 
was once an object of an active and flourishing commerce; it was for- 
merly even exported to England, but since the government of Venice 
has given the exclusive privilege to the national manufacture, its expor- 
tation has ceased, or has very much diminished. 
5. Kaolin of Saxony and Prussia, 
The manufactory of porcelain at Meissen, in Saxony, is justly cele- 
brated. The earth is found in the vicinity of Scheeberg. The quarries 
are explored by wells and galleries; they yield only about 400 quintals 
of earth annually; it possesses the same character as the French, and 
the mode of manufacture is much the same. 
6. Kaolin of England, 
The kaolin of England is associated with the ores of tin. It is found 
particularly in Cornwall. This association ought not to be forgotten in 
this country, as it is well established that the ores of this valuable me- 
tal belong only to granitic rocks. The earth in Cornwall presents no 
characters to distinguish it from the same earth in other countries. It 
is, therefore, unnecessary to extend my remarks upon it, as they would 
only form repetitions of what has been already stated. 
Besides the kaolin which results from the decomposition of granite, 
another material has been substituted in the manufacture of porcelain. 
It is a carbonate of magnesia mixed with a small per centage of silex. 
It is a white compact earth, and often resembles the white calcareous clays. 
It softens in water, but does not form a paste with it, except after a 
long pounding and maceration. It effervesces with acids, and is cover- 
ed with saline efflorescences, after being moistened with dilute sulphuric 
acid; when exposed to the blowpipe, it hardens, but does not fuse, ex- 
cept on the sharp corners of the fragments the most exposed to heat. 
This substance, besides being employed in the porcelain manufacture, is 
made into pipes, for which it is well adapted. 
