The author
takes two parts of the former to three of the latter, and prepares an
intimate, finely divided mixture, which is kept ready for use.
Of this mixture four parts are taken to one of zircon, thoroughly
mixed, and melted in a platinum crucible at a red heat. The mass fuses
readily, froths at first and gives off bubbles of gas, and flows then
quietly, forming a very fluid melt. If the zircon is finely ground, 15
minutes are sufficient for this operation. The loss of weight is 16
per cent., and is not notably increased on prolonged fusion. It
corresponds approximately to the weight of the carbonic anhydride
present in the potassium carbonate.
As pungent vapors are given off during fusion, the operation should be
conducted under a draught hood. The activity of the mixture in
attacking zircon appears from the following experiment: Two zircon
crystals, each weighing 1/2 grm., were introduced into the melted
mixture and subjected to prolonged heat. In a short time they
decreased perceptibly in size; each of them broke up into two
fragments, and within an hour they were entirely dissolved. The melted
mass is poured upon a dry metal plate, and when congealed is thrown
into water. It is at once intersected with a number of fissures, which
facilitate pulverization. This process is the more necessary as the
unbroken mass is very slowly attacked by water even on prolonged
boiling.
Pages:
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135