G. W. Hawes—Inquid Carbon dioxide in Smoky Quartz. 205 
water. It therefore gathers into a globule, and the liquid now 
takes its place as the inner zone. In such cavities again the 
inner zone grows smaller and disappears at a temperature below 
the critical point of the carbon dioxide, and’ the smaller the 
inner globule is, the quicker it will evaporate into the zone of 
vapor. In such cavities the line which divides the water from 
the middle zone is much blacker, and more deeply shaded, 
because the difference in the indices of refraction of water and 
ed of carbon dioxide is much greater than between water 
and liquid carbon dioxide. 
Cavities in Branchville quartz containing water and liquid and gaseous carbon 
dioxide in variable proportions, magnified fifty diameters. 
Figs. 7 and 8 represent cavities in which if carbon dioxide 
exists, it is not in sufficient amount to be condensed to liquid 
form, and in which the volume of water is relatively much 
larger. These cavities, therefore, possess but two zones, the 
outer of water, the inner of vapor. The temperature at which 
Such bubble disappear is very much higher and dependent 
Upon their size. 
No relationship between the position of the cavities and the 
Telative size or method of arrangement of the three zones 
