[ 3i9 ] 
by a mineral Spring, appears from the few follow- 
ing Obfervations. They do not ferment with 
Acids, Spirit and Oil of Vitriol. The Solution of 
this Stone in Aquafortis gives a beautiful red Tinc- 
ture, and in Oil of Vitriol leaves a Tin&ure of a 
brown dark Red. The woody Part of thefe Stones 
in Aqua fortis alfo gives a red Tin&ure, tho* fome- 
what paler ; and, when taken out of the Liquor, 
fhews red Spots in its Pores, which I take to be Par- 
ticles of Iron and Sulphur: Thefe Spots, when the 
Wood began to dry, became black ; and the Wood,, 
when dry, turned of the Colour of a deep red 
Jefuifs-Bark. 
In fome of thefe Stones, feveral curious Veins, of 
a red and bluifh Colour, are very remarkable, being 
intermixed with black and white Stride- 
Having broken fome of thefe Stones, I found 
in the Infide a kind of white, and feveral Clutters of 
frnali white and black angular Cryftais, which throL 
the Microfcope appear tranfparent, and of different 
Shapes, but moftly hexagonal. I difeovered fuch 
Cryftais in fome of the woody Part of thefe Stones. 
One Piece of a white Stone I calcined in a Crm 
cible for 24 Hours, but could neither reduce it to 
Coal or Lime. The Powder yielded faintly to the 
Magnet. This Stone was found in the Ground at 
fome Diftance from the Lake. 
One Piece of a black Stone, found in the Lake, 
I likewife calcined for 24 Hours, and could not re- 
duce it to Coal or Lime: The Powder yielded briskly 
to the Magnet. 
I calcined one Piece of another Stone, about one 
Inch thick, for about 4 Hours, in an intenfe Fire, 
S f until 
