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A Descriptive Catalogue of Diamonds in the Cabinet of Abraham Hume
Abraham Hume,Jacques Louis Bournon
No preview available - 2015
aggregation angle belonging angle nearly angle of nearly angles are replaced Angles of incidence AVē calculation Catalogue convex Count de Bournon crystalline laminae deeply striated diagonal diamond perfectly different retirements direction dode dron edges are replaced elongated dodecaedron faces flattened dodecaedron fluate of lime green earth integral molecule intermediate modification intermediate retirement large diamond laws of crystallization lens macle formed middle mineral substances Mineralogy modification represented modification which replaces nearly of 165 observed obtuse occasioned octae octaedral diamond octaedron by four ofits ofthe owing parallel perfect diamond belonging planes belonging planes form planes of replacement preceding Number primitive crystal primitive form primitive octaedron prism produced regular octaedron regular tetraedron remain replace the edges reunion rhombic planes rhomboid of 60 rows 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 14 - 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 x - 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 xi - 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 x - 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 ix - In these openings or voids, the planes forming their partitions would be in an inclined position, deviating from the axis which would
Page x - substance whose primitive form is octaedral, we shall see that the regular tetraedrons which would then form their integral
Page ix - to me difficult to admit. According to this theory, the substance to which it was applied would contain a
Page 1 - the passage, in a very advanced state, of the regular octaedron to the acute rhomboid of 60° and 120",
Page x - than the other. If, on the other hand, we observe the construction which,