270 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



similar to those of Sulpbur Bauk, tbougb incapable of dissolving cinnabar under the 

 physical conditions existing at the surface, would bold it in solution at higher tem- 

 peratures and pressures. Such waters rising toward the surface would deposit the 

 entire quantity of cinnabar held in solution before reaching the atmosphere. 



This discovery seems to furnish an entirely satisfactory explanation of the absence 

 of cinnabar from the original surface of the Sulphur Bank and of the failure to find 

 mercury in the water. It also removes all reasonable doubt that the deposits of cur- 

 'dy, hydrous silica containing cinnabar are really as recent as they appear and that 

 the ore is still accumulating at this interesting locality. The experiment furthermore 

 affords an actual instance of the precipitation of an important ore by relief of temper- 

 ature and pressure, a method of deposition the evidence of which is generally imperfect 

 and indirect. 



