MINERALOGY. 
115 
gillaceous earth, both becaufe they become brittle 
in the fire, which is a proof that they harden, 
and becaufe they become more fufible by the ad- 
mixtion of a martial earth t but the method na- 
ture makes ufe of for this change is as unknown, 
as it might perhaps in other refpecfts be necefifary, 
hot to force the earths together, for fome flight 
reafon, within the compafs of a few orders. 
The Siberian Afbeftus, which may be confidered 
as the principal and chief of the fibrous kind, is, 
as it were, confumed by the flame of a blow- 
pipe, and does not leave any more certain mark 
of fiifion ^ but it melts readily with borax to a 
clear and colourlefs glafs. 
The natural ilore of this , kind is in proportion 
to its ceconomical ufe, both being very inconfi- 
derabie. It is an old tradition, that in former 
ages they made cloaths of the fibrous afbefti^ 
which is faid to be exprefled by the word Byjfus ; 
but it is not very probable, fince, if one may 
conclude from fome trifles now^a-days made of it^ 
as bags, ribbons, and other things, fuch a drefs 
could neither have an agreeable appearance, nor 
be of any convCniency or advantage. It is more 
probable that the Scythians drefifed their dead 
bodies, which v/ere to be burnt, in a cloth ma- 
il ufadlii red of this flone ; and this has perhaps oc^ 
cafioned the above fable. 
Paper is likewife made fforh' this ftorie, only to 
fhew its fixity in the fire, and to procure lome 
efteem and value to this ciirious fubftance. 
It was reported fome years ago, that the French 
fearched for afbefti, in order to mix it with the 
tar for preferving houfes and jhips *, but the 
queftion is, If the afbefti can be of more fervice 
than pounded mica, or charcoahdufl: employed to 
the fame purpofe? 
1 2 SECT. 
