Refractions crystals

The pentoxide S3N2O5 can also be made directly from S4N4 and SO3. It forms colourless, strongly refracting crystals which readily hydrolyse to sulfamic acid ... 

Sir David Brewster 1781-1868, Scottish physicist famous for his researches on tire absorption, reflection, refraction, and polarization of light, and on doubly refracting crystals. One of the founders of the British Association for die Advancement of Science. He invented the kaleidoscope and improved the stereoscope. His optical researches led to great improvement in the construction of lighthouses. 

In interference microscopy the illumination is split into two beams [1,2]. The beam splitter is a half-silvered mirror. In reflection, one beam is reflected from the sample, while the other is reflected from a flat reference mirror [20-22]. Transmission is more complex as the beam splitter may be a double refracting crystal, and the two beams can be displaced horizontally or vertically [20-22], In all cases the two beams are recombined so that they interfere. The interference pattern can be used to measure the specimen thickness in transmission or the specimen roughness in reflection. 

Orthorhombic, highly refractive crystals sublimes at room temperature decomposes at 130°C explodes at 210°C.1... 

Potassium hydrazoate, KN3.—On concentrating a solution of hydra-zoic acid neutralized with potassium hydroxide, the hydrazoate separates in doubly refracting crystals. It is not very explosive, but melts and decomposes above 350° C. The aqueous solution has a slight alkaline reaction, the solubility at 17° C. being 49-6 grams per 100 grams of water.3... 

Calcium phosphate reacts with potassium hydrogen sulphate and sulphuric acid to form potassium dihydrogen phosphate, KH2PQ4, the most important of the potassium phosphates. It forms doubly refracting crystals melting at 96° C.,5 of density 2-33256 at 9-2° C., and 2-3387 at 20° C., and of specific heat 0-208 between 17° and 48° C.8 The heat of formation in aqueous solution is 374-4 Cal.9 When heated at 244° C., it loses water, yielding the acid pyrophosphate, K2H2P207.10... 

Ammonium perchlorate, NH4C104.—The perchlorate is formed by mixing solutions of barium perchlorate and ammonium sulphate, by the action of ammonium nitrate on sodium perchlorate,8 and by that of ammonium chloride on calcium or magnesium perchlorate.10 It forms rhombic,11 doubly refracting crystals,12 of density 1 88 at 25° C. Its solubility at 18° C. is 21 07 grams in 100 grams of water.18 It is de-... 

Cupric metaborate, Cu(BQ2)2.—The metaborate is prepared by fusing cupric nitrate with excess of boric acid.1 It forms blue, doubly refracting crystals, density 3-86, and is also known as a hard, vitreous substance of density 3-6. 

PROP Refractive crystals or white solid which readily sublimes water-sol. D 4.6 16°, subl 600°. Very sol in HF. IDLH 50 mg/m (as Zr). 

Carbon occurs in nature in its elementary state in two allotropic forms diamond, the hardest substance known, which often forms beautiful transparent and highly refractive crystals, used as gems (Fig. f)M poorer stones are used as an industrial abrasive) and graphite, a... 

Cyclomercuri pentamethylene, M.pt. 120° C., forms hard, white, rhombic, doubly refracting crystals from a mixture of benzene-light petroleum. It is readily soluble in cold ether, light petroleum, or benzene, with difficulty in water. Its molecular weight as determined by the ebullioseopic method is about 360 (270 calc.), and this apj)ears to corres x>nd to a simple ring. v. Braun, however, points out that a comparison of the boiling-points of the pentamethylene series of eom-... 

Brewster, D. On the laws which regulate the absorption of polarized light b> doubly refracting crystals. Phil. Trans. 1, 11-28 (1819). 

Orthorhombic, highly refractive crystals. Sublimes at room temp. Sinters at 90 dec at 130" explodes at 210. Bums with a luminous flame. d 1.77. Vapor pressure (mm) 0.04 ((F) 1.0 (480 66.5 (1other organic solvents. Solns or impure solid dec by light. LDM in mice 100 mg/kg i.v., Strohmeier, Z. Naturforsch. 19b, 540 (1964). 

Although this method was used initially to grow very refractive crystals of high melting point (because Czrochralski equipment was not adequate to attain the high temperatures needed), recent improvements in... 

Colorless, highly refractive crystals very hygroscopic, deliquesce on exposure to air. Soluble in water and alcohol with hydrolysis sparingly soluble in CSg and chloroform hydrolyzes in alkali hydroxide solutions. Concentrated HaS04 dissolves NbFg somewhat more readily than TaFg. 

Diamond (r.d. 332) occurs naturally and can be produced synthetically. It is extremely hard and has highly refractive crystals. The hardness of diamond results from the covalent crystal structure, in which each carbon atom is ilnloed by covalent bonds to four others situated at the comers of a tetrahedron. The C-C bond length is 0.154 mn and the bond angle is 109.5°. 

A completely odorless product is obtained by sublimation of the recrystallized carbonyl at 0.5 mm. or less, and at a bath temperature of 40 to 50° . the large, highly refractive crystals are collected in a receiver cooled with Dry Ice. The sublimation apparatus must have a short, wide bore connection between the hot and cold sections to prevent clogging with crystals. The loss of product in the crystallization and sublimation processes is slight several runs... 

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