Ground-glass surfaces

Ensure that all the individual components in the assembly are adequately supported when in position the friction between contiguous ground-glass surfaces does not provide adequate support. Therefore always use clamps, the claws of which are lined with rubber or other soft material. When assembling apparatus, allow some play in the clamps until the individual parts are in position, and then secure the position of the assembly by gently increasing the pressure of the clamps. 

Lubrication of all ground glass surfaces is essential for distillations under reduced pressure. Suitable lubricants are Apiezon grease L, M or N and Silicone stopcock grease also Alkathene (a polyethylene plastic), which is especially suitable for high temperatures. 

Diffusion Cell System A diffusion cell system with a standard open cap ground glass surface with 15 mm diameter orifice and total diameter of 25 mm. 

Gaseous diazomethane may explode on ground glass surfaces and when heated to about 100°C. Safety precautions for the use of diazomethane have been published.2-7 Alkali Metals. Explodes on contact.2... 

Figure 3. Electrolysis cell. A, B, fritted glass disks C. electrolytic junction between solution and reference electrode D, platinum grid E, magnetic stirrer (in Teflon) F, Teflon gasket G, Torion stopper, H, glass tube J, ground glass surfaces K, locking screw L, bubbler. (From Ref. 48.)...

Figure 1. Schematic of the equipment used to dialyze dilute solutions against a mixed solvent solution chamber, C, solvent chamber, C dialysis membrane, M supporting glass frits, F ground glass surface, S teflon-coated magnetic stirrer, T solvent inlet, I outlet, O, teflon tubing. A fresh solvent reservoir, R and solvent waste, W. The chambers hold approximately 20 mL each.

The drying time of an oil is the time required to obtain a dried continuous thin him under the specihed conditions of the standard ASTM D 1640-69 method. In this method, an oil-coated thin him on a ground glass surface is cured at 23-25°C under 50-100% relative humidity. Vegetable oils have also been characterised spectroscopically to determine their structure. This is done by a variety of spectroscopic methods. A brief description of these methods is presented below. 

However, if the glass surface is not a smooth plane, such as a ground glass surface, some of the light wiU be scattered diffusely, rather than reflected in a single direction. For this... 

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