10 DR BREWSTER on the Existence of Two New Fluids 



In one specimen of Amethyst I was enabled to determine, 

 that the angle of total reflexion took place at 51 26', and, con- 

 sequently, that the refractive power of the Fluid, or m, was 

 m' + sin 51 26' 1.21066, m' being taken equal to 1.5484, the 

 ordinary refractive power of Amethyst. 



Many other details might have been added under the present 

 head, in support of these conclusions ; but they are necessarily 

 reserved for the next section, with which they have a more im- 

 mediate connection. 



2. Cymophane or Chrysoberylfrom Brazil. 



In several specimens of this mineral I have discovered strata 

 of cavities, which contain the new fluid. One of these is re- 

 markable for having two strata parallel to one another ; one of 

 which, about yth of an inch square, contains no fewer than 30,000 

 cavities, filled with the new fluid, which expands and fills the 

 cavity with the heat of the hand. The cavities are in general 

 very small ; but I succeeded in determining that the vacuities all 

 reappear simultaneously, at a temperature of 



3. Quartz-Crystals from Quebec. 



In examining the crystals of quartz from Quebec, I have 

 found that almost every specimen of it contains cavities with the 

 new fluid. 



In one crystal the vacuity reappeared at 76. Another va- 

 cuity in the same crystal reappeared at 80 ; while another, al- 

 most in contact with this, required a temperature of 125 to 

 make the fluid fill the cavity. 



: In another specimen of the crystals there are cavities where 

 the new fluid expands fully ^d of its bulk, by an additional tem- 

 perature of 30 ; and though they are very shallow, the vacuities 

 reappear in the form of several smaller vacuities, and exhibit an 

 appearance as if the fluid were thick and viscid. 



