Histoi'y of MechankcH Moe^htim^. 
Sapphire.-^ 
-The composition for this paste is, 
Strass, very white, 
0.9855 
Oxide of Cobalt, very pure, 
0.0145 
3.0000 
This mixture 
must be put into a Hessian crucible, carefully 
luted, and remain thirty hours in the fire. If the process i& 
well conducted, the result will be a 
very hard glass, without 
bubbles. 
Amethyst . — 
-Very deep amethyst may be obtained with 
Strass, 
0.9870 
Oxide of Manganese, 
0.0078 
Oxide of Cobalt, 
0.0050 
Purple of Cassius, 
0.000^ 
1.0000 
M. Lan^on 
uses. 
Strass, 
0.9977 
Oxide of Manganese, 
0,0022 
Oxide of Cobalt, 
0.0001 
1.0000 
Beryl or Aquamarine is made with 
Strass, 
0.9926 
Glass of Antimony, 
0.0070 
Oxide of Cobalt, 
0.0004 
1.0000 
. Syrian Garnet. — This paste is used for small jewels, and is 
made with 
Strass, 
0.6630 
Glass of Antimony, 
0.3320 
Purple of Cassius, 
0.0025 
Oxide of Manganese, 
0.0025’ 
1.0000 
In the fabrication of the pastes, many precautions are neces- 
sary, which can be learned only by experience. The materials 
should in general be carefully pulverised. The mixtures should 
be properly sifted, and the same sieve should not be used for 
different compositions. In order to obtain the glass well melted, 
and homogeneous, and without striae and bubbles, materials of 
great purity must be employed ; — they must be mixed in a state 
of extreme tenuity the best crucibles must be used ; — ^the fire 
