Geoscience Reference
In-Depth Information
selection of a suitable autoclave to withstand the pressure at high temperatures over
a long period of time. It was soon after Chroustshoff
[16]
proposed the gold lining
for the steel autoclaves that many earlier researchers began to work on new designs
and new lining materials for autoclaves to obtain the most ideal conditions for the
synthesis of several high temperature oxide minerals. Probably, Friedel and Sarasin
[20]
termed their hydrothermal autoclave as hydrothermal bomb because of the
high-pressure working conditions in their experiments. Obviously, new metals and
alloys available during that time were tested. For example, De Schulten
[25]
even
used a copper bomb to synthesize analcite by heating a mixture of sodium silicate,
sodium aluminate, and lime water at 180
C for 18 h. Similarly, Sir Ramsay and
Hunter
[26]
used a cast iron bomb. Bruhns
[27]
used steel bombs lined with plati-
num, with a cover held down by bolts and made tight by means of a copper washer,
which was protected by the action of the mineralizer on platinum. Other contempo-
rary workers used this design. Perhaps, the simplest design of the autoclave, made
of a nickeled gun-barrel or silver-lined steel tube closed by a screw cap and copper
washer, was developed by Doetler
[28]
. Using this type of autoclave, Doetler has
done extensive work by obtaining several mineral recrystallized species like chaba-
zite, okenite, heulandite, analcite, and natrolite. However, in most of these works
from 1870s to 1890s, using the above-mentioned type of autoclaves, experimental
uncertainties were introduced owing to the lack of a perfectly tight closure, which
resulted in the leakage of water, thereby causing variations in the pressure condi-
tions (and hence the concentration) of water during the course of experiments.
Friedel
[29]
obtained corundum crystals by heating a solution of NaOH with an
excess of Al
2
O
3
at a higher temperature at that time, 530
535
C.
Toward the end of the nineteenth century, Spezia
[5]
from the Torino Academy
of Science began his classical work on the seeded growth of quartz. His contribu-
tion to the field of hydrothermal research is remembered even today. The early
works showed that plates of quartz kept at 27
C for several months with water
under a pressure 1750
2
1850 atm did not lose its weight and also showed no etch
figures. Thus, he concluded that pressure alone has no influence on the solubility
of quartz
[30]
. Subsequently, Spezia
[30]
studied the action of Na
2
SiO
3
in the
solubility of quartz with temperature. He found that when alkali was present in the
system, SiO
2
separated out as quartz and the rhombohedral faces of the quartz were
easily attacked, and on the other hand, on the same faces were the greatest deposi-
tions of SiO
2
from Na
2
SiO
3
solutions. The more rapid growth of the quartz crystals
along the c-axis was explained.
During the nineteenth century, much work was done on the geological side of
hydrothermal research and the entire work was confined to Europe, particularly
Germany, France, Italy, and Switzerland. It was only toward the turn of the nine-
teenth century that the science of hydrothermal technology moved to North
America, which was assisted by the American Industrial Revolution. Further, the
establishment of the Geophysical Laboratory at the Carnegie Institute of
Washington, USA, in 1907, probably marked the most important milestone in the
history of hydrothermal technology. Although a great deal of research was carried
out on hydrothermal
2
technology in the nineteenth century,
the facilities for
