Properties of the Two New Fluids in Minerals. 425 



fluid does not expand perceptibly by heat, and is in all probabi- 

 lity water. When the specimen is shaken, the fluid becomes tur- 

 bid, and of a whitish colour, arising from a fine white sediment, 

 which settles in the lower part of the cavity. 



In a specimen of Quartz from Brazil belonging to Mr SPA- 

 DEN, there is a cavity with an air-bubble, about the tenth of an 

 inch long. It is nearly one-third full of a white powder, con- 

 sisting of crystalline particles, which, upon inverting the speci- 

 men, flow over the surface of the air-bubble like sand in a sand- 

 glass. In the specimens of quartz already mentioned in page 417. 

 as containing cavities with pyramidal summits, there is only one 

 fluid, in which there is generally an air-bubble. These cavities 

 often contain opaque spherical balls *, which are distinctly move- 

 able ; and in one cavity I have counted ten of these balls, seven 

 of which roll about the cavity when the specimen is turned 

 round f . In a second specimen, spherical balls of the same kind 

 are copiously disseminated in the quartz, and exist also in the ca- 

 vities. In a third specimen, the balls occur near the summits of 

 the pyramidal cavities, some of them being within and some of 

 them without the cavity. 



In the crystallisations of ice several phenomena occur, which 

 are intimately connected with the preceding inquiry. When 

 water is frozen in a glass vessel, the ice is often intersected with 

 strata of cavities, which have the same general form and aspect 



* These balls are of the same size as the seeds of Lycopodium, which amount to 

 32 parts of Dr YOUNG'S eriometrical scale. Their diameter is therefore 5555 B -r- 32 

 = j5 T th part of an inch. 



f- I have since opened several of these cavities by the blow of a hammer. In a 

 second or two the fluid was entirely gone, without leaving a trace of its existence be- 

 hind. The spherical balls remained in the cavities. They were not acted upon 

 either by the muriatic or the sulphuric acids. 



3 H2 



