Of WHINSrONE and LAV J, 89 



In the next place, the undiffolved refiduum -was mixed with 

 twice its weight of very pure cauitic potafh, and expofed to a 

 low red heat, for an hour, in a filver crucible. The mafs was 

 then diluted with water, fuperfaturated flightly with nitric acid, 

 and filtered. With this folution nitrate of barytes produced no 

 effect ; confequently, thefe experiments lhow, that the (tone in 

 queftion does not contain any traces of fulphuric acid. With 

 nitrate of filver, however, the folution gave a white precipitate, 

 more abundant than the two preceding. The different portions 

 of muriate of filver, being collected, and dried on a fand bath, 

 weighed only 4 grains. 



As a fourth part of muriate of filver confifts of acid, accord- 

 ing to the moft correct: experiments hitherto publifhed, thefe 4 

 grains confequently indicate, in 100 parts of this bafalt, only a- 

 bout one of muriatic acid. All the whins and lavas, to be men- 

 tioned in the remaining part of this paper, were found, by a fi« 

 milar procefs, to contain about the fame quantity. 



According to the refults of thefe different proceffes, there are, 

 in 100 parts of the bafalt of Staffa, 



Silex, 48 



Argil, - . . rf 



Oxydofiron, - - - 16 



Lime, o 



Moifture, and other vol. matter, - 5 



Soda, about - - - - 4 



Muriatic acid, about - - - 1 



99 



I have thus detailed exactly the various experiments per- 

 formed in analyzing this fpecies. As all the other whins, and 

 the lavas, which follow, were analyzed in the fame manner, and 



Part r - M exhibited 



