APPENDIX, 141 



POSTSCRIPT TO THE HISTORY. 



ON Monday, the 4th of November 1793, Dr Hope, Pro- 

 fefibr of Medicine in the Univerfity of Glafgow, read a paper, 

 entitled, An Account of a Mineral from Strontian f and of a peculiar 

 Species of Earth which it contains. Want of room, and the length 

 of the difTertation, prevent its appearance in the prefent volume. 

 But as the difcovery of a new earth cannot fail to be interefting, 

 it has been thought proper to trefpafs a little on the order of 

 time, and to infert here the following abftracl. 



The mineral is found in the lead-mine of Strontian in Argyle- 

 fhire. It was brought to Edinburgh about fix years ago in confi- 

 derable quantity. It was generally received as the aerated barytes. 

 At that time, Dr Hope had fome doubts of its being the barytic 

 fpar, and ufed, in his prelections, when he filled the chemical chair 

 in the Univerfity of Glafgow, to mention fuch of its diftin- 

 guifhing characters as he had then difcovered. The Strontian 

 fpar fometimes is colourlefs, oftener it has a greenifh or yel- 

 lowilh hue. Its texture is fibrous, and it frequently (hoots in- 

 to cryftals, which are (lender fpiculse or hexagonal columns. 

 The fpecific gravity of it goes from 3.650 to 3.726. 



This mineral is infipid, and requires nearly 800 times its 

 weight of water to diflolve it. It effervefces with acids, and 

 during folution carbonic acid is diTengaged to the amount of 

 30.2 grains per cent. When moderately heated, it crackles, 

 and lofes its tranfparency. By a very vehement heat, the car- 

 bonic acid is expelled, and the mafs lofes 38.79 per cent, of its 

 weight, and ceafes to effervefce with acids. The calcined fpar, 

 when water is poured on it, fwells burfts, and becomes hot in 

 a greater degree, and with more rapidity, than lime. It is 



acrid, 



