Part IH. Of Regular Stones. 309 
A lamp of the TALK-ROCK near Spiral, in the upper 
Carinthia. Given by Dr. Edward Brown. It confifteth of 
broken pieces, -like thofe of the Selenites , immerfed in a 
white glofly Stone, flamed with purplifh fpots, and fo hard 
as to fcratch Glafs. 
Talk. , although flexible, and regularly figur’d, yet feel- 
eth no Acid ; and is of that obftinate nature, as neither to 
melt, nor fcarce loofe its colour, in the fire. Confidering 
which, and that all Salts, yet known, will flow: I am in¬ 
duced to think, That it hath not its Figure from any Salt 3 
but is almoft a Ample Earth fui generis. And that there are 
earthy Particles,as well as Saline; which are regularly figur’d, 
and of which this and fome other Stones are compofed. 
Hereof is prepared a wa(h for the Face, which fome Chy - 
myfts cry up for the beft in the World. 
A GREEN TALK-SPAR. The whole piece, is here of 
a rude Figure 3 but is eafily broken into Rhomboid Plates, 
rcfembling thofe of Talk , from whence I have nam’d it. 
’Tis tinged with a pale Green. It ftirreth not with any 
Acid. Yet is not flexible, as true Talk , but brittle as Glafs. 
A great Cryftalline TALK-SPAR. So I call it. Sent by 
Dr. Erafmus Bartholine , together with a large account of 
it, publidled in a the Phil. Tranfactions. ( a ) And by the 
Dr. (/;) himfelf in a diftinft Treatise. ’Tis a foot long, ^ a <b) Experi- 
foot broad, and two inches and ■; thick. Of a Rhomboid 
Figure, and the narrow fides likewife floaped, as in the ci Dif-Di- 
Cryjials of Talk It breaketh alfo into parts of the fame 
Figure, or near it. Yet not flexible, but brittle. Polite, 
colourlefs, and tranfparent, as tlie cleareft Chryftal. Yet 
foft and difloluble efpecially with Nitrous Spirits 3 and by 
a ftrong fire reduceable to a Calx. Of a very different na¬ 
ture from Cryjlal, although the faid Dr. is pleafed fo to call 
it. When heated, it is of an EleChick Nature, or like Amber, 
taketh up ftraws and other light Bodies. That which he 
principally Notes is, That the Objects feen through it, in 
certain pofitions, appear fometimes Angle, fometimes 
double, and fometimes Axfold. Which he afcribes to a 
Refraction peculiar to this Stone. And to me, it feerns pro¬ 
bable , That tins various Refraction depends upon the 
{fracture of the Stone, fc. as it is not one piece abfolutely 
entire, but compofed of feveral Plates 3 and thofe not all 
in 
