PHILOSOPHICAL TRANSACTIONS. [aNNO 1705. 



the best ears could but just distinguish it : it appearing to them like a small 

 shrill sound as at a great distance. On suffering the air gradually to re-enter, 

 it was easy to perceive the increase of sound at the different times the bell was 

 made to ring: the recipient being again replete with air, the sound then seemed 

 something more clear and audible than at its first inclusion. 



Concerning the Figures of the Salts of Crystal. By M. Leuwenhoeck,, F, J?. S. 



N° 298, p. 1906. 

 M. Valkenier, from Switzerland, showed me some crystals that were very 

 remarkable ; one as large as my fist, which looked like several small flint-stones 

 joined together ; they seemed to be united by very transparent particles, which 

 might be called wild crystal ; the largest prominent points of which seemed no 

 larger through the microscope than a large grain of sand ; many of them ap- 

 peared to be hexangular, like the mountain crystal. The same gentleman fur- 

 ther told me, that in some of the highest mountains in Switzerland, the large 

 and small stones were almost mixed or united with the wild crystal ; which 

 mountains are therefore called by the inhabitants nagelfelsen, that is, the nail 

 mountains or rocks, by reason of the great number of prominent points 

 in them. 



I struck off 4 or 5 small flint stones from the great piece; in doing which, 

 several of the wild crystal particles came off together ; to which I placed a 

 microscope, and observed that almost each of them was of a different figure, 

 though most of them ran into a hexangular point, of several sizes; in breaking' 

 them from one another, the sides assumed particular figures, which looked as 

 if they were composed of nothing but long particles, all of them as bright and 

 transparent as any crystal, excepting only in those parts where they were 

 joined to the stones. The crystal particles lay very thick upon one another ; 

 and they were so small, that 100 and more were not equal to one of our 

 crystal particles ; among others, I observed some no larger than a coarse grain 

 of sand, which were composed of 100 other smaller particles, all very trans- 

 parenti and appearing through the glass like a little mountain of crystal, form- 

 ing a very agreeable spectacle. 



sril saw likewise several crystal particles, which, instead of ending in one 

 hexangular point, like others, consisted of several sharp ones, some of which 

 were very different both in length and thickness from the rest ; which con- 

 firmed my opinion, that they were coagulated out of long particles. 



I observed, that where the little flint stones had not lain very close to one 

 another, the void space, as it appeared to the naked eye, had also been filled 

 with the crystal matter ; but when I came to view them more narrowly, I could 



