A System of Crystallography, with Its Application to Mineralogy

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R. Griffin, 1841 - Crystallography - 469 pages

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Page 96 - The experiment is repeated with all the alterations thought necessary, till we may consider ourselves arrived at a fair estimate, which is at last expressed by the number of that degree with which it has been found to agree nearest, the decimals being likewise added, if required. The files answering best for the purpose are fine and very hard ones. Their absolute hardness is of no consequence ; hence every file will be applicable, whose hardness is in the necessary relation with that of the mineral....
Page xxvi - The same number of atoms combined in the same way produce the same crystalline form, and the same crystalline form is independent of the chemical nature of the atoms, and is determined only by their number and relative position.
Page 3 - A rhomboid is that which has its opposite sides equal to one another, but all its sides are not equal, nor its angles right angles.
Page 96 - ... process alone is not sufficient, if we intend to make a more sure and extensive application of the characters that may be taken from hardness, than that which has hitherto been common in Mineralogy. But if we take several specimens of one and the same mineral, and pass them over a fine file, we shall find that an equal force will everywhere produce an equal effect, provided that the parts of the mineral in contact with the file be of a similar size, so that the one does not present to the file...
Page 145 - Instructions for the Multiplication of Works of Art in Metal by Voltaic Electricity: with an introductory chapter on Electro-chemical decompositions by feeble currents.
Page 124 - After remarking that the mathematician positively knows that the sum of the three angles of a triangle is equal to two right angles...
Page 4 - Such angles are right angles. An angle less than a right angle is called an acute angle. An angle greater than a right angle is called an obtuse angle.
Page xxiii - In this case, both hardness and specific gravity are prominent characters, and exclude the individual at once from the first and third, but not from the second class : with the characters of this class, its other properties also perfectly agree. Hence the individual belongs to the second class. Comparing the properties of the individual with the characters of the orders in the second class ; hardness and specific gravity will be found too great for the order Haloide ; hardness too great for the orders...
Page ix - Whewell, esq. was read, on a General Method of calculating the Angles made by any Planes of Crystals, and the laws according to which they are formed.
Page 15 - The difference between an angle and a right angle is called the complement of that angle. — Thus...

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