GEOLOCtCAL OBSERVATFONS IN FRANtJE. 295 



To (leterririfie its'po^^er of resisting friction, it raay ^ Jfiji'^g^iat^it. 

 nibbed with sand ; and if this scratch it more readily than 

 it does a glaze known to be good, we may be assured it is 



soft. 



If vinegar be boiled for some hours in a vessel coated with y■'nep^^^^l 

 • -t. » t , 11-1 *• dissolve us 



a soft ghize, it will attack the glaze, and dissolve a portion jt^^d, 



of its lead, which w.ll ])c precipitated from the vinegar on ., 



the addition of a few drops of sulphuric acid, commonly 



called oil of vitriol. 



, But a method more within eveiy one*s reach, and there- '»k a ready 



fore deserving to be known, is, to let fall a drop of strong 



ink on a piece of earthen-ware, dry it before the fire, and 



then wash it. If tbe glaze be too soft, the ink will leave oa 



it a slight spot. 



XL 



Heights of vartovs Places in France, ^'c. ; bt/ Dr, Berger. 

 Continued^ from p, i217. 



Sect. H. 



Heights ascertained during a tour in the ci-devant Promnce of 

 Auvergjie, 



JL HE following observations were collected in a tour made Tour in A.u- 

 in the spring of 1802, in company with Mr. Leopold von vergne. 

 Buch, a celebrated Prussian mineralogist, and Mr. A* Ju- 

 rine. With these gentlemen 1 set out from Geneva to visit 

 the chain of the mountains Dome and d'Or, traversing the 

 ci-devant provinces of Bugey, Bresse, Lyonnois, and Forez, 

 and returning through Dauphiny. As all this country, par- 

 ticularly the most interesting, which is for the greater part 

 included in the circle forming the department of Puy-de- 

 ,Porae, has been carefully exaiuiued by several able mine- 

 'i»logists, I shall say little respecting its physical constita- 

 tion. Most of the heights were calculated by Mr. von Buch 

 from the simple formula of tlie difference of the logarithms 

 of the numt)ers expressmg the heights of the barometers at 

 ' • , the 



