gio. = Dr. Wiruerine’s Experiments and Obfervations 
More obvious Properties. 
Somewhat glofly like fatin; yellowith-white, opake; com- 
pofed of flender {picule fet clofe together, and pointing from a 
center. | | 
In fome pieces there are concentric circles of a femi-tranfpa- 
rent horn like appearance. It is not very brittle; may be 
fhaved with a knife; lofes little or nothing of its weight by 
being made red-hot. Its fpecific gravity 4,000; but after 
foaking one night in the water 4,200, or more. 
Ek PE RO MOE NPs. 
When treated in the fame manner that the Derbyfhire cauk 
was, in the preceding feCtion, 100 parts of it appeared to 
contain 
Marmor metallicum = 9757 
‘Calciform iron - - 253 
100 
Sufpeting that the prefence of fo {mall a proportion of iron 
could hardly occafion the whole of the apparent differences be- 
twixt the Shropfhire and Derbyfhire cauks and the marmor 
metallicum ; and thinking it not improbable, that they might 
contain lead; I mixed fome of them with charcoal-duft and 
borax, but could not by means of the blow-pipe produce any me- 
tallic appearance, although vitriol of lead, treated in the fame 
manner, was readily reduced. 
Ithen mixed four parts of cauk with one part of vitriol of 
lead; the lead could {till be reduced, though not fo readily as 
befere. 
GENEBAL 
