33 £ Count de Bournon's Observations on a new 
be inclined to consider these two substances as distinct from 
each other. 
I shall now take a short view of the analogy, and of the dif- 
ference, existing in the characters of the two substances just 
mentioned. 
Their specific gravity is nearly the same. The AbbO Hauy 
states that of the Arragonite at 294,6. I found that of the hard 
carbonate of lime to be 2912. 
The hardness of the latter is rather greater than that of the 
former : it scratches the Arragonite, but is not scratched by it. 
The Arragonite is seldom found without a tinge, more or 
less considerable, of purple; but I have never observed any 
appearance of colour in the hard carbonate of lime. 
The Arragonite, when thrown upon a heated iron, emits a 
very brilliant phosphorescent light, of a yellowish-orange colour. 
The other substance, when treated in the same manner, pro- 
duces only a white phosphorescent light, scarcely perceptible. 
From the Arragonite is obtained, by splitting, a rhomboidal 
tetraedral prism, of 1 16 0 and 64° ; and, from the hard carbonate 
of lime, one of 128° and 52 0 . 
The last-mentioned substance, in its secondary forms, passes 
into a hexaedral prism, which has two edges of 128°, and four 
others of n6°. Whereas, the Arragonite becomes a hexaedral 
prism only in consequence of the union of several of its rhom- 
boidal prisms ; and as, in that state, three of the edges of the 
prism are formed by the union of the edges of 64°, belonging to 
the tetraedral prism, it has three angles of 11 6°, and three 
others of 128°. This gives 732 0 , for the whole measure of the 
angles of the prism ; Which measure is too great by 1 2 0 ; and is 
the cause that, in the formation of the prism, the rhomboids 
of which it is composed, are obliged sometimes to penetrate 
