210 A. W. Wright—Gases in Smoky Quartz. 
the sharp fragments of the mineral were shot off with such 
violence as to destroy them immediately. Recourse was there- 
fore had to a porcelain tube about one centimeter in diameter, 
glazed inside. This was carefully cleaned with pure distilled 
water, one end stopped with a plug cemented in, and the other 
provided with a perforated brass cap, into which could be 
screwed a piece through which passed a slender glass tube, 
the joint being rendered tight by a thin washer of india-rubber 
or paper. The closed end of the tube was filled for some 12 
centimeters with pieces of clean glass rod, and upon these 
rested a loose plug of calcined asbestus. The quartz, broken mto 
fragments of such a size as to permit their entrance, was Grop- 
ped into the tube, filling it to within 10 or 12 centimeters of 
ing any her ae elevation of the temperature of the ce 
ment joints. 
rendered absolutely free from leakage. 
The pump having been kept in action until no gas appeared 
to pass down, heat was cautiously applied to the tube, ane 
For the more careful analyses two portions of the rock abi 
selected representing the greatest differences in the materia 
‘: = 
