ANNALS 



OF 



PHILOSOPHY. 



DECEMBER, 1820. 



Article I. 



'Chemical Analysis of the Needlestone from Kilpairick, in Dum- 

 bartonshire. By Thomas Thomson, M.D. F.R.S. 



1 HE term zeolite was first introduced into mineralogy by 

 Cronstedt, and appHed by him in the Transactions of the Aca- 

 demy of Sciences of Stockholm for the year 1756, to a mineral 

 possessing the following characters : 



1 . A little harder than fluor and calcareous spar. Scratched 

 by steel, and not giving sparks with that metal. 



2. Melts easily by itself in the fire, and froths up as borax 

 does into a white porous slag, which cannot, without great difl&- 

 culty, be brought to a solid and transparent state. 



3. It is more easily dissolved in the fire, when mixed with 

 soda, than with borax or microcosmic salt. 



4. It does not effervesce with microcosmic salt as calcareous 

 spar does, nor with borax as is the case with gypsum. 



5. It dissolves very slowly, and without any effervescence in 

 acids, as in sulphuric and nitric acids. If concentrated sulphuric, 

 acid be poured on pounded zeolite, a heat arises, and the powder 

 unites into a mass. 



6. In the very moment of fusion, it gives out a phosphoric 

 light.* 



When Cronsledt published his paper on Zeolite, he does not 

 seem to have been acquainted with that mineral in a regularly 

 crystallized form ; but some years afterwards several new varie- 



• Magellan's Cronstedt'* Mineralogy, p. 944. 



Vol. XVI. N° VI. 2 C 



