Crystals needle-shape

White crystals, needle-shaped to prismatic stable in moist air in dry air, loses water at the surface poisonous sensitive to reducing agents. On heating to 40°C, converts to the anhydrous salt. Very readily soluble in water 100 g. of solution contains about 68 g. of NagSeOg SHgO at 20°C. 

Colorless crystals, needle-shaped and tabular. Solubility in HgO decreases with increasing temperature can be recrystallized only from solutions containing phosphoric acid. Soluble in dilute acids and dilute ammonia. Loses twomoles of HgO at 100°C, a third mole at 190°C the anhydrous salt is obtained at about 250°C. d 3.109. Hardness 2-3. Crystal structure orthorhombic. 

Nicotinic acid is an amphoteric soHd with needle-shaped crystals. It is less soluble than nicotinamide and its poor solubihty in diethyl ether can be... 

Fibrous Composites. These composites consist of fibers in a matrix. The fibers may be short or discontinuous and randomly arranged continuous filaments arranged parallel to each other in the form of woven rovings (coUections of bundles of continuous filaments) or braided (8). In the case of chopped strand mat the random arrangement is planar. In whisker (needle-shaped crystals or filaments of carbon and ceramics) reinforced materials the arrangement is usually three-dimensional and the resulting composites are macroscopically homogeneous. 

Evaporation to dryness under reduced pressure gives 20.9-22.1 g. (90-95%) of crude product. Purification by recrystallization from 500 ml. of pentane yields 15.5 g. (67%) of p-nitrobenzyl fluoride as colorless needle-shaped crystals, m.p. 36-37 (Note 2). 

The product crystals find industrial application as a component raw material for optical glass, fibreglass, Braun tubes, electric condensers, barium ferrite, etc. Needles shaped crystals are obtained at high pH, while pillar-shaped crystals are formed at neutral pH. The formation of carboxyl ions is via hydroxy ions at high pH, but at neutral pH it may accompany the production of hydrogen sulphide, as... 

Rtathon.— Make strong solutions of. about eciuivalent quantities of n.Liihthalene and picric acid in acetic acid, or alcohol, and pour them together. (Jn coolin q yellow, needle-shaped crystals of n.iphthalene picrate separ.ate C IL(N0 )30H ni. p. 

Sublimation.—A poition of the dry subsiam.c may be purified by sublimation. It is placed (2—3 gtamsj on a l.irge uatch-glass, which is heated on the sand-bath ovei a vcia small flame. The watch-glass is covered with a sheet of filter papei, which is kept flat by a funnel ]daced above. After five minutes or so pale yellow, needle-shaped crystals of anthraquinone will have sublimed on to the filter ptiper. 

Cineol forms a number of crystalline derivatives, amongst which may be mentioned the hydrobromide, CjgHjgO. HBr, melting at 56°, and the compound with iodol, CjdHjgO. C I NH, which forms yellowish-green crystals, melting at 112°. It also forms a crystalline compound with resorcinol, which has been used as a basis for its quantitative determination. This compound consists of 2 molecules of cineol with 1 of resorcin, and forms needle-shaped crystals, melting at 80°. 

Mfldelchen, n, little needle (or pin), I adel-eisenerz, n., -eisenstein, m. needle iron ore (gdthite in acicular crystals), -erz, n, needle ore (aikinite in acicular crystals), -faser, /, acicular fiber. nadelfSrmig, a. needle-shaped, acicular. Madel-holz, n. conifers (collectively), esp, pines and firs wood of conifers, soft wood, -holzer, n.pl. (Bot.) Finales, Coniferae, -holzkohle,/. soft-wood charcoal, -holzteer, m, soft-wood tar, (loosely) pine tar. -holzzellstoff, m. cellulose (or pulp) from conifers, nadelig, a. needly, acicular. 

The compound appears in the form of a white powder or of needle-shaped crystals (MP = 147°C to 149°C), which are tasteless and odorless. 

Small needle-shaped single crystals were examined by transmission electron microscopy (TEM) and electron diffraction (ED) (see Fig. 16-17). The results show that the crystals are elongated along the b-axis, which is the direction of weak intermolecular n-n interactions, and have a well-developed (ab) top surface. It corresponds to the surface of aliphatic tails (direction of weak intermolecular interactions). There are indications of displacement of successive ( / )-laycrs along the fl-axis, in line with the other signs of disorder in the aliphatic layer. 

The preparation of oriented polymers by the method of the directed polymerization is of interest since it is possible to avoid the complex process of disentangling the macromolecules already packed randomly in the bulk of the unoriented polymer. However, methods involving conversion of these needle-shaped crystals into actual fibres have not yet been developed. 

White or off-white needle-shaped water-soluble crystals. 

From 95 g of SOCI2 and 183 g of H2S , both dissolved in CS2 and added simultaneously but slowly (within 8 h) to a mixture of 0.75 1 CS2 and 0.35 1 Me20, ca. 4 g of pure SgO were obtained after repeated recrystallization. SgO forms needle-shaped yellow crystals of m.p. 78 °C (dec.). The molecules consists of a crown-shaped Sg rings with exocyclic oxygen atoms in axial positions [89]. 

Colorless or white needle-shaped crystals with a pungent odor. Used as a preservative in taxidermy. 

Ephedrine (17) was known to give coloured products on exposure to sunlight. When a 1 % solution was irradiated with UV light from a 30 W tube the solution became coloured and colourless needle-shaped crystals separated. With prolonged exposure, the crystals redissolved as the solution darkened to an intense brown. On analysis, the crystalline compound was identified as the oxazolidine (18). This compound was known to be formed by reaction between ephedrine and benzaldehyde, so it was assumed that the primary photodegradation product of the drug was benzaldehyde [27]. 

Experiment 10.—A few bubbles of hydrogen chloride are passed into a solution of a few cubic centimetres of acetaldehyde in twice as much absolute ether kept cold in a freezing mixture. After a short time the metaldehyde separates in magnificent needle-shaped crystals which are filtered with suction and washed with ether. The filtrate yields a second crop on repeating the treatment. 

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