of 0 XFO %V^S H1%E. ij^ 
nary (lone prove fo advantagious, what would one of them do, if 
the Joifts and Laths at leaft were made of the Cornifi w arming- jiom^ 
that will hold heat well eight or ten hours ? or of Spanifi Ruggi- 
ola^s^ which are broad//^3t/e5 like //7e^, cut out of a Mountain of 
red fait near Cardona^ which being well heated on both fides, will 
keep warm 24 hours 7 
92. To which may be added the Invention of making G/^^y^s- 
of flones^ and fome other materials^ at Henly upon Thames^ lately 
brought into England by Seignior de Cofla a Montferratees^ and car- 
ryed on by one Mr. Raven/croft^ who has a Patent for the fole 
making them ; and lately by one Mr. BiJ/jop, The materials they 
ufed formerly were the blacked Flints calcined, and a white Cbri- 
jlalline fand, adding to each pound of thefe^ as it was found by 
folution of their whole mixture, by the ingenious Dr. Ludwell 
Fellow of Wadham College^ about two ounces of ^i/^r, Tartar^ and 
Borax. 
93. But the Glaffes made of thefe being fubjeft to that unpar- 
donable fault called Crizclling^ caufed by the two great quanti- 
ties of the Salts in the mixture, which either by the adventitious 
Niter of the Jir from without, or warm liquors put in them, 
would be either increafed or dijfolved ; and thereby indure a Sca- 
hrities or dull roughnefs, irrecoverably clouding the tranfparency 
of iht glafs ^ they have chofen rather fince to make their glaffes 
of a great fort of white Febbles^ which as! am informed they 
h?ve from the River Fo in /laly ; to which adding the aforemen- 
tioned JaitSj but abating in the'proportions, they now make a fort 
of Pebble glafs^ which are hard, durable, and whiter than any 
from Venice^ and will not Crizel^ but endure the fevereft trials 
whatever, to be known from the former by a Seal fet purpofely 
on them. 
94. And yet I guefs that the difference, in refpeft of Crizeling^ 
betw^een the prefent Glajs and the former, lies not fo much in the 
Cah^ the Pebbles being Pyrites (non€ but fuch I prefume being fit 
for vitrification') as well as the Flints ; but rather wholly in the a- 
batement of the falts^ for there are fome of the Flint gl^jfes ftriO:- 
ly fo called (whereof I have one by me) that has endured alltry- 
alsas wallas rhefe/^. But if it be found otherwife, that wbite 
fei^Z'/fi- are really fitter for their turns thzn. black Flints, 1 think 
See M.r,W/l/ughl>ys Voynge through 5^<?;>. />. 471. 
they 
