[ 2 7 2 ] 
where no dirty or dark- colour'd Loam, Mineral, or 
opaque Stones prevail : So we may conclude in gene- 
ra!, that if, during the Fluidity of thefe Bodies, no 
metallic or mineral Fume, no Drift, Clay, or Sand, 
was imbibed, the Water and lapidcous Juice make up 
a clear pellucid Mafs. If the Cafe was other wife, 
whatever Impurities the Waters contracted, and had 
not at the time of forming difeharged, are ftill to be 
feen in the Stone. 
Sect. 7. 
Of their Hardness. 
As to the Hardnefs of our Cornij), ) Cryftals, all I 
have to obferve is, that they cut well into Seals, when 
they have no Flaws: Their natural Points alfo will 
cut Glafs 5 but not freely or deep ; in which Particu- 
lar they fall much fhort of the true Diamond. 
Conjectures relating to the Properties of the true 
j D iamond . 
Of this I fhall not pretend to aflign any other 
Reafon, than that the true Diamond feems to have 
more lapideous Juice included, and more intimately 
and congenially united under an equal Surface, than 
any other Body in the World. It has alfo very little 
Salt in it, as Dr. Grew obferves ( CoJ'mol . p. 14.) 5 and 
his Opinion is confirmed by its being found in fuch 
fmall Mafies; and by its great Weight it can have little 
Water; both which Obfervations arc fupported by 
its great Refiftance, and almoft Immutability in Fire : 
So that the true Diamond has little Salt, and little 
Water, confiding almoft intirely of ftony Juice con- 
creted ; 
