art III. Of Regular Stones. 509 
A lump 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 gloffy Stone, ftainedwith purplifh fpots, and fo hard 
as to fcratch Glafs. 
Talk.-, although flexible, and regularly figurd, yet feel- 
cth no Acid $ and is of that obftinate nature, as neither to 
melt, nor fcarce loofe its colour, in the fire. Considering 
which, and that all Salts, yet known, will flow : I am in- 
duced to think, That it hath not its Figure from any Salt 5 
but is almoft a fimple Earth fai generis. And that there are 
earthy Particles,as well as Saline, which, are regularly tight d, 
and of which this and fome other Stones are compofed. 
Hereof is prepared a wafh for the Face, which fome Cby- 
myfts cry up for the beft in the World. 
A GREEN TALK-SPAR. The whole piece, is here of 
a rude Figure 5 but is eafily broken into Rhomboid Plates, 
refembling thofe of Tall^, from whence I have nam'd it. 
'Tis tinged with a pale Green. It ftirrcth not with any 
Acid. Yet is not flexible, as true Talk. , but brittle as Glafs. 
A great CryftaUine TALK-SPAR. So I call it. Sent by 
Dr. Erafmus Bartboline, together with a large account of 
it, publifhed in a the Phil. TranJ anions, {a) And by the^ Num - tf 7- 
Dr. (b) himfelf in a diftincl: Treatife. Tis a foot long, ^ a (hi Experi- 
foot broad, and two inches and ? thick. Of a Rhomboid S/ma^di- 
Figure , and the narrow fides likewife lloaped, as in the ci Dif-Di- 
Cryftals of Talk, It breaketh alfo into parts of the fame acIaft,C1, 
Figure, or near it. Yet not flexible, but brittle. Polite, 
colourlefs , and tranfparent, as the cleareft Chryftal. Yet 
foft and diffoluble efpecially with Nitrous Spirits $ and by 
a ftrong fire reduceable to a Calx. Of a very different na- 
ture from Cryflal, although the faid Dr. is pleafed fo to call 
it. When heated, it is of an Eleffrick. 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 fingle , fometimes 
double, and fometimes fixfold. Which he afcnbes to a 
RefraElion peculiar to this Stone. And to me, it feems pro- 
bable , That this various Refraction depends upon the 
ftructure of the Stone, fc. as it is not one piece abfolutely 
entire, but compofed of feveral Plates $ and thofe not all 
in 
