OTHER GLASSES

A shallow metal vessel containing sand, the so-called sand bath, heated by means of a flame, was formerly employed for heating flasks and other glass apparatus. Owing to the low heat conductivity of sand, the temperature control is poor the use of sand baths is therefore not... 

Electrical. Glasses are used in the electrical and electronic industries as insulators, lamp envelopes, cathode ray tubes, and encapsulators and protectors for microcircuit components, etc. Besides their abiUty to seal to metals and other glasses and to hold a vacuum and resist chemical attack, their electrical properties can be tailored to meet a wide range of needs. Generally, a glass has a high electrical resistivity, a high resistance to dielectric breakdown, and a low power factor and dielectric loss. 

Fig. 12. Glass manufacture. Temperatures are for common soda—lime glass. Other glasses may require appreciably different temperatures.

Other glass-ceramics may find potential use in Hquid crystal and electroluminescent displays. 

Other Glass III Antiarrhythmic Agents. Clofihum phosphate is a benzene-butanaminium derivative that has highly specific Class III antiarrhythmic activity. It is orahy active, has a rapid onset of action, and a reasonably long duration of antiarrhythmic activity. In preliminary clinical studies, clofihum has shown efficacy against spontaneous ventricular tachycardias (69). 

There are many appHcations in which glass is used as an electrical insulator. One example is glass-to-metal seals. Moreover, other glasses are useful as a result of ionic or electronic conductivity. 

Glass-reinforced grades of SAN exhibit a modulus several times that of the unfilled polymer and, as with other glass-filled polymers, a reduced coefficient of thermal expansion and lower moulding shrinkage. The materials are thus of interest on account of their high stiffness and dimensional stability. 

M.L. Williams, R.E. Landel, and J.D. Ferry, The temperature dependence of relaxation mechanisms in amorphous polymers and other glass-forming Uquids, J. Am. Chem. Soc., 77, 3701-3707, 1955. 

The working characteristics of the other glasses mentioned can usually be deduced from their expansion coefficients. A glass of lower expansion than Monax needs an oxygenated flame, and one with higher expansion needs only a gas-air flame. 

The spindle makes a very useful handle for holding the tube while other glass-blowing is carried out, and owing to its much reduced diameter it does not become hot when the tubing is worked near to the end. The tip of the spindle can be cut off to attach a rubber tube for blowing. If for any reason an accurately central spindle is... 

Byrex Chemical Resistance Glass has a Young s modulus of 6-1 x 10 dynes/cm , a modulus of rigidity of 2-5 x 10 dynes/cm and a Poisson s ratio of 0-22. Similar values are found for other glasses. 

The extension of an amorphous material under a tensile force can be resolved into three parts first, an immediate elastic extension. Which is immediately recoverable on removing the tensile force Mcondly, a delayed elastic extension which is recoverable slowly and thirdly, a plastic extension, viscous flow, or creep, which cannot be glteovered. With glass at ordinary temperatures, this plastic exten- ion is practically absent. A very slow delayed elastic extension OOCUrs. This effect can be troublesome in work with torsion fibres. The delayed elastic effect in vitreous silica fibres is 100 times less than in other glass fibres, and viscous flow of silica is negligible below OO C (N. J. Tighe, 1956). For exact work vitreous sihea torsion flbres are therefore used. 

H. 6. Jennings, "Comparison of Fused Silica and Other Glass Columns in Gas Chromatography", Huethig, Heidelberg, 1981. 

See Other GLASS INCIDENTS, GAS EVOLUTION INCIDENTS See Other METAL HALIDES... 

See other glass incidents See other non-metal halides... 

See other GLASS INCIDENTS, gas evolution incidents See related boranes... 

See other GLASS INCIDENTS See other HALOGEN OXIDES... 

See other glass incidents, halogenation incidents Ammonia... 

Dining preparation of tungsten(IV) dibromide oxide, appropriate proportions of reactants are heated in an evacuated sealed glass ampoule to 400-500°C. Initially only one end should be heated to prevent excessive pressure bursting the ampoule. See other GLASS INCIDENTS See other halogens, oxidants... 

See Hydrogen peroxide Acetic acid, or Acetic anhydride, or Vinyl acetate See peroxyacids (references 5,6) See other GLASS INCIDENTS... 

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