[ 2 73 ] 
creted j to which Properties its great Hardncfs may 
therefore be attributed : Whereas in our Diamonds 
there is much Salt, and much Water (comparatively 
fpeaking); which two Ingredients, mix'd with the 
iapideous Juice, may incline thofe Bodies to be more 
friable and tender, and deprive them of that Hardncfs, 
which a lefs-reduccd lapidific Juice would certainly 
have had. This ferns to me the real Caufe of the 
true Diamond’s Hardnefs, and of our falfe ones fall- 
ing as much fhort of it in this Particular, as in Luftre : 
But I muft acknowlege, that, for want of fufficient 
Experiments relating to both, I cannot decide per- 
emptorily. However, by weighing the Cornijh Dia- 
monds in Water, I find they are generally to the 
Weight of our common Watter, at a Medium, as 
io -i is to 4 5 and I apprehend, that if they had more 
Iapideous Particles, they would weigh more, as they 
find the true Diamond really does *. I find alfo the 
cleared and brighteft Cornijh Diamonds weigh much 
heavier than the other which are more fhady and 
opaque. That they have much Salt alfo, may be con- 
cluded from their being projected fometimes into 
fuch large, regular, hexagonal Columns. 
Sect. 8. 
Of the Texture of Cornifh Diamonds. 
There are fome little Varieties in the Texture of 
our Cornifh Diamonds, which are fometimes to be ob- 
ferved in their broken Sides and Edges ; but always, 
and more diftin&ly, in their Bafe. Some are uni- 
form, of one Colour and Tranfparency throughout ; 
M m fome 
* The Weight of Cryflah to Water is as 2 f to 1 . of D iamoyds as 
3 1 to 1. See thefe Tranfadtions, No. 488. p. 451. C. M. 
