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aggregation angle belonging angle nearly angle of nearly angles are replaced Angles of incidence brown tint calculation Catalogue combination convex Count de Bournon crystalline laminae deeply striated diagonal diamond perfectly different retirements direction distinctly dode dron edges are replaced elongated dodecaedron equilateral triangle exhibits faces flattened dodecaedron fluate of lime green earth integral molecule intermediate modification intermediate retirement large diamond laws of crystallization lens middle mineral substances Mineralogy modification represented modification which replaces nearly of 165 observed obtuse occasioned octae octaedral diamond octaedron by four owing parallel perfect diamond belonging planes belonging planes form planes of replacement preceding Number primitive crystal primitive form primitive octaedron produced regular octaedron regular shape regular tetraedron remain replace the edges reunion rhombic planes rhomboid of 60 single plane small diamond belonging solid angles spinel striae superb diamond surface taken place termediate traces transparent triangular segment triedral pyramid variety whilst white colour yellow colour
Page 16 - 52. A very perfect transparent dodecaedral diamond, the planes of which are divided into two, according to their small, as well as to their large diagonal, but their faces are all rounded in consequence of the crystallization having proceeded successively by a great number of retirements in the direction of its two diagonals.
Page xii - would be, that, whilst among the substances in which the power of cohesion extends itself over the entire surface of the molecules, we should meet with those in which the power of cohesion between their integral molecules is the weakest; those substances in which that power between the integral molecules is the most
Page xiii - sensible indications of natural joints passing through their edges. I then became thoroughly persuaded that, in point of fact, the integral molecule of the regular octaedron could not possibly be the regular tetraedron ; but, at the same time, I confess that, with all the researches I have since made, I have not been able to satisfy myself respecting the form of this molecule.
Page xii - they should deviate from the surface of the substance ; a form, most assuredly, the best adapted for absorbing the light which would fall on the empty space within, or fittest for reflecting on the surface of the body the smallest possible portion of the rays of light which would strike upon it. That construction, therefore, which, by its nature, would absorb the moiety, nearly, of the light
Page xi - In these openings or voids, the planes forming their partitions would be in an inclined position, deviating from the axis which would
Page xii - substance whose primitive form is octaedral, we shall see that the regular tetraedrons which would then form their integral
Page xi - to me difficult to admit. According to this theory, the substance to which it was applied would contain a
Page 3 - the passage, in a very advanced state, of the regular octaedron to the acute rhomboid of 60° and 120",
Page xii - than the other. If, on the other hand, we observe the construction which,