C 3^5 ) 
4« Fhofphorm Me tailor urn, 
TAke Laph Smaragdi Miner alis (fuch as is found iti 
the Mines of Saxony) and beat it into a very fine 
Powder, 
If you ftrcvv this very fine on any Metal, and in any 
Figure, and ftt the Plate on any hot Coals, in a ftiort 
time you will perceive in the Dark, a Light to sliioe^ 
which will (faith my Author) laft as long 33 you conti- 
nue the hot Coals, and if you beat out the Fire, it may 
do again for once or twice, but then the Vertue will 
fade. 
V. Fart of Two Letters from Dr. Cay, to Dr. 
Martin Lifter, Fellow of the Colledge of Fhy- 
fecials and Koyal Society ; concerning fome 
Mineral Waters. 
I Had a Mineral Water feot me, not long fince, by 
Mr. Duncan ( a Surgeon in Alnfekk^ pretty well 
known for his Skill in his own Profeffion) which he de- 
fired me to examine, and give him an account of. Ac- 
cordingly I firft try'd it after the ufu^I manner, with 
Galls, and found it turn'd almoft quite Black, though it 
had been brought at leaft Thirty Miles by Land- carnage 
from Eglingham in Morthumherland : But if this deep 
Cdlour was fomewhat of a Surprize to me (for it was 
deeper than that of any atramentous Water, I had ever 
met with before) yet you'il eafily imagine, tliat ! was 
mnch. more furpriz'd to find, after I had flowiy, in a 
Glais, evaporated more than one half of this Water^ that 
it 
