Cryptography
the art of writing in secret characters or cipher, or with sympathetic ink. The simplest method consists in choosing for every letter of the alphabet sor some sign, or another letter or group of letters. Even the more complex, however, present, as a rule, only temporary difficulty to an expert. ring letter in the English language is letter e, that the common double vowels are ea and ou, that r, s, and t are the most frequent terminal letters, etc., are of no small assistance in forming a key to any given cryptogram.
CIPHER WRITING.
See are of no small assistance in forming a animal of Madagascar, forming a genus CIPHER WRITING. but resembles a weasel, three feet long, and attacks the largest animals with great ferocity. parts.
CRYSTAL (ice), in chemistry and mineralogy, a clear transparent body, which, by the mutual attraction of its particles, has assumed the form of some one of the regular geometric solids, being bounded by a certain number of plane which, by the mutual attraction of its particles, has assumed the form of some First, plane surfaces, called faces, which are said to be similar when they are equal to each other and are similarly situated; dissimilar, when they are unequal or have a different position .
Second, edges, formed by the meeting of two faces. They are said to be similar they are equal to each other and are lar, by dissimilar faces. Equal edges are formed when the faces are inclined at the same angle to one another; unequal, when they are inclined at different the meeting of three or more faces; and in this case also they are similar and disangles. Third, solid angles, formed by the meeting of three or more faces; and in this case also they are similar and dissimilar, equal and unequal angled edges. The chemist procures crystals either by ring them in a fluid and then abfusing the bodies by heat and then allowing them gradually to cool, or by disdrawn through the crystal, and called its axes. There are seven of these systems, six of which refer to three axes and one solving crystals (now universally adopted) is based upon certain imaginary lines axes. There are seven of these systems, drawn through the crystal, and called its not (chinometric). six of which refer to three axes and one to four, and they are subdivided according as the axes are at right angles (orchometric) When the axes are equal and at right angles the system is called isometric.
When the angles are right angles, but all unequal, the system only two are equal, the system is called orthorhombic. The classes are tetragonal. When the three axes are at lar, or cubic system, in which the axes are equal and at right angles to one another; second, the square prismatic or are equal and at right angles to one at right angles to each other, and while two are equal, the third is longer or lar, or cubic system, in which the axes dimetric system, in which the axes are at right angles to each other, and while rhombic, or trimetric system, in which the axes are at right angles to each other, but all are of different lengths; two are equal, the third is longer or shorter; third, the right prismatic, the axes are at right angles to each or other, but all are of different lengths; one plane inclined to each other at 60 system, which has four axes, three in degrees, the fourth perpendicular to this plane; fifth, the monoclinic or oblique system, in which two axes are at right angles and the third is inclined to their system, in which two axes are at right plane; sixth, the diclinic right angles, the third oblique to both; seventh, the triclinic system, in which the three axes are inclined to each other oblique system, in which two axes are at the three axes are inclined to each other right angles, the third oblique to both; at any angle other than a right angle. or doubly The power of forming crystals is poscombinations whether natural or artifi- The power of forming crystals is poscial, and also by a large number of organic chemical bodies. The degree of this capacity varies greatly in different substances, so that certain chemical comothers rarely. Bodies which entirely lack the power of forming crystals or crystalline aggregates are called amorphic. The size of crystals also varies greatly. Some are very large, others are crystalline aggregates are called amor- phic. The size of crystals also varies greatly. Some are very large, others are tals. The infinitesimally small crystals are called microliths. Crystals grow by the deposit of new horizontal layers CRYSTALS CRYSTALS / 2 3 4 5 6 7 8 9 10 00000 DOAV 12 15 16 H 17 13 14 - 18 19 20 21 22 23 24 25 CRYSTALS 26 T No. 1, Octahedron; No. 2, Hexahedron No. 3, Rhombic Dodekahedron; No. 4, Tetra-Hexahedron; No. 5, Triakisicosahedron; No. 6, Icositetrahedron; No. 7, Hexoctahedron; Nos. 8 and 9, Combination of Hexa and Octahedron; No. 10, Combination of Hexahedron and Dodekahedron; No. 11, Combination of Octahedron and Dodekahedron; Nos. 12, 13, 14, 15 and 16, Various combinations of regular systems; No. 17, Derivation of Tetrahedron from an Octahedron; No. 18, Trigonal Dodekahedron; No. 19, Deltahedron; No. 20, Hexakisoctahedron or Hexoctahedron; No. 21, Pentagonal Dodekahedron; No. 22, Dyakisdodekahedron or Diploid; No. 23, Tetragonal Protopyramid; No. 24, Tetragonal Deuteropyramid; No. 25, Ditetragonal Pyramid; No. 26, Tetragonal combinations. CRYSTALLINE ROCKS on their surfaces, always keeping the characteristic angles exactly the same.
Even when the growth of crystals in different directions takes place, with untakes pla place, with unequal rapidity, and distorted forms arise, as is often the case, the law still holds good, the inclination of the adjacent planes and the angles which they enclose are the same. Hence the importance and the value of crystallometry and the science of crystallography or crystalology. Crystals occur with an almost infinite variety of forms-calcareous spar having alone more than 200 forms in more than a thousand different combinations, and some crystals have as many as 300 different sides. But all crystals may be grouped in accordance with certain systems .