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PLATES I AND II. Crystals.

1. Regular System.-a. Homohedral. Fig. 1-12.

6. Hemihedral.-.. Tetrahedron. Fig. 13—17.-B. Pentagonal Dodecahedron. Fig. 18—20.

2. Square Prismatic or Four-membered System.a. Homohedral. Fig. 21-39.

21 and 22: Anatase ;—23, 29: Zircon ;-24, 27, 33: Molybdate of lead ;—25, 26: Hydrated ferrocyanide of potassium ;-28, 39: Vesuvian; -30: Acid phosphate of potash (K 0, 2H O, POS + 2H 0) or acid arseniate of potash (K O, 2H O, As Os + 2H 0);—31: Sulphate, seleniate, or chromate of silver and ammonia;–32: Apophyllite ;-34: Cyanide of mercury ;35: Nickel-speiss;—36: Sulphate or seleniaté of zinc or nickel; -38: Calomel.

b. Hemihedral. Fig. 40.--Parasulphat-ammon. 3. Two and two-membered or Right Prismatic System. Fig. 41-80.

41-44: Sulphur; 45: Tartar-emetic;—46: Iodine ;—47, 48: Sulphate of lead; -49: Sulphate of baryta;50: Nitrate of silver;—51, 52: Chloride of barium;53: Hyperchlorate or hypermanganate of potash or ammonia; -54–58: Nitrate of potash ;-59: Sulphate or seleniate of silver or soda, and hypermanganate of baryta ;—60: Camphor of cubebs ;—61–63: Acid phosphate of soda, crystalline system 1--Acid phosphate or arseniate of soda. System 2;65: Morphia;—66: Hyposulphate of silver; -67, 68: Mellitate of ammonia ;—69: Bicarbonate of ammonia;—70: Protochloride of mercury;—71, 72: Sulphate of magnesia;—73: Sulphate of zinc or nickel ;--74: Indigo;—75: Chloride of mercury, copper, and potassium ;-76, 77: Neutral sulphate of ammonia, or neutral sulphate, seleniate, chromate, or manganate of potash;—78: Oxalate of ammonia; -79: Citric acid ;—80. Rochelle salt.

4. Two-and-one-membered or Oblique Prismatic System.--a. The base making an oblique angle with the obtuse lateral edge of the rhombic prism. Fig. 81–100.

81, 87: Iodide, bromide, or chloride of potassiam with four atoms of water;–82: Chondrodite;—83: Chlorate of potash ;-Sulphate of magnesia and potash ;-85: Sulphate of nickel and potash ;-86: Chromate of ammonia;—88: Hypermanganate of silver;-89: Pyrophosphate of soda ;-90: Bicarbonate of potash.

b. The acute lateral edge of the rhombic prism making an oblique angle with the base. Fig. 101–116.

91, 92: Augite ;-93-95: Neutral phosphate of ammonia (2N H'O, HO, POS + 24H 0) or arseniate of ammonia ;-96—100 : Ordinary phosphate of soda (2Na O, HO, POS + 24H O) or arseniate of soda; 101, 102: Phosphate or arseniate of soda and ammonia;—103, 105: Borax ;—106: Acetate of lead ;-107, 108: Phosphate or arseniate of soda and potash ;-109: Tartaric acid;-110: Acetate of copper ;-111:

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