124 TERMINOLOGY. 



in the electric phenomena is very often accompanied by a different 

 configuration of the opposite terminations of crystals. (. 50, p. 47.) 

 The phenomena relating to the electricity of minerals have not, 

 hitherto, been found very useful in mineralogy : they have rather 

 excited attention, as physical curiosities, than as important charac- 

 ters. For this reason, the apparatus required for observing these 

 phenomena will not be described in the present treatise. It may be 

 found, however, in most works relating to the subject, which the 

 student can consult in case he wishes to enter upon these investi- 

 gations. 



. 102. TASTE. 

 Several minerals produce a sensible taste. 



All the acids and many of the salts produce some taste. The so- 

 luble salts not occuring, in general, with any of the characters re- 

 quired for their exact determination, their taste is almost the only 

 one left to which we are able to recur ; accordingly, it has been 

 found useful to provide the differences in the kinds of taste with 

 particular denominations. The following expressions have been 

 adopted : 



1. Astringent for the taste of Vitriol. 



2. Sweetish for the taste of Alum. 



3. Saline for the taste of Common Salt. 



4. Alkaline for the taste of Carbonate of Soda. 



5. Cooling for the taste of Salt-petre. 



6. Bitter for the taste of Epsom salt. 



7. Urinous for the taste of Sal-ammoniac. 



8. Sour for the taste of Sulphuric acid. 



Besides, the intensity or other peculiarities of several kinds of taste 

 may be indicated, which will be done in the progress of the work 

 in a manner sufficiently plain to be understood, without farther ex- 

 planation in this place. 



. 103. ODOR.* 



There are minerals which, either spontaneously or when 

 rubbed, emit some odor. 



