Gypsum plate

In addition to reflectance measurements, the pellets were studied microscopically employing a gypsum plate. This is one of the most effective ways of observing coke differences without relying on mechanical measurements. The appearance of the various constituents of the coke, whether flat, mottled or striated and the degree of anisotropy readily indicated the type of coal from which the coke is produced (1). Utilizing the gypsum plate, microscopically this natural coke appeared striated and anisotropic. Production coke from a low volatile coal has this same appearance. 

The identification of n" and n in a crystal of unknown orientation may be obtained with the help of a crystal plate of known orientation and birefringence (Fig. 4.29). The polarizing microscope is equipped with a gypsum plate with birefringence d n" — n ) = 551 nm (red in the first order). Colors of addition and subtraction are obtained according to the orientation of the unknown crystal with respect to the plate. 

Figure 16.35 (Plate 1). All strontium myristate. Top left lOOx crossed polars - room-temperature lamellar. Top right lOOx crossed polars 90°C - lamellar. Middle left lOOx crossed polars, gypsum plate in, heated to 218°C - rhombohedral. Middle right 200 x crossed polars, gypsum plate in, cooled from rhombohedral-cubic phase boundary, oscillated near 210-215°C - rhombohedral (bright) and cubic (dark). Bottom left lOOx parallel polars, cooled to 210 from 218°C - cubic to rhombohedral transition. Bottom right 200 x crossed polars, gypsum plate in, cooled from 290°C and oscillated near 260° C - hexagonal...

Figure 16.35 (Plate 5). Top left lanthanum myristate (Lamy), lOOx crossed polars, gypsum plate in, 120.TC - smectic C. Top right Lamy, lOOx crossed polars, gypsum plate in, 152.3°C - smectic C Middle left lanthanum palmitate, lOOx crossed polars, gypsum plate in, 126.3°C - smectic C. Middle right Lamy, lOOx crossed polars, gypsum plate in, 152.3°C - immediately post melting. Bottom left cerium stearate (Cest), lOOx crossed polars, 79.6°C - lamellar. Bottom right Cest, lOOx crossed polars, gypsum plate in, 124.0°C - smectic C...

Plate 4 All lead myristate. Top left lOOX crossed polars, gypsum plate in, cooled from melt into (crystalline... 

FIG U RE 12.1 Product of the mass transfer Stanton number (St = k/ut) and Schmidt number (Sc = v/D) vs plate Reynolds number (Re = u LIv) with Schmidt number as parameter (Modified from the original Higashino, M. and M.G. Stefan. 2004. Water Environmental Research 76, 292-300.) kc is the water-side mass transfer coefficient at the sediment-water interface (cmh ), V is the kinematic viscosity of water (cm h ), Z) is the diffusivity of gypsum in water (cm h ), is the friction velocity at the sediment-water interface (cmh ), L is the gypsum plate length (cm). 

Typical applications in the chemical field (Beaver, op. cit.) include detarring of manufactured gas, removal of acid mist and impurities in contact sulfuric acid plants, recovery of phosphoric acid mists, removal of dusts in gases from roasters, sintering machines, calciners, cement and lime Idlns, blast furnaces, carbon-black furnaces, regenerators on fluid-catalyst units, chemical-recoveiy furnaces in soda and sulfate pulp mills, and gypsum kettles. Figure 17-74 shows a vertical-flow steel-plate-type precipitator similar to a type used for catalyst-dust collection in certain fluid-catalyst plants. 

A thin layer of adsorbent is applied to a support that may be a sheet of glass, metal, or plastic (Figure 13.4, D). Adsorbents are typically alumina, silica gel, or cellulose and may be mixed with gypsum to aid in adhering to the support. They may also include a fluorescent indicator that aids in visualization once the plate is developed. These adsorbents may also have hydrocarbons attached to them such that reverse-phase TLC can be carried out. 

Interestingly, these precoated TLC-plates essentially have first, a special abrasive-resistant layer containing no gypsum and secondly, the layer contains a reliable fluorescent indicator that is excited to emit a fluorescence under either a short-wave or a long-wave UV light. 

The cleaning process usually washes out the CaS04 originally present as binder. Therefore, the silica gel thus obtained by purification may be reused to prepare TLC-plates with other appropriate binders like gypsum, starch etc. 

Phosphatidylinositols are separated on a gypsum-free silica plate, saturated with a 1% potassium oxalate solution in water, and activated as described above. The recommended solvent is Soln. 2. A second run with the same solvent after an intermediate drying increases the separation performance. 

This manipulation requires that the mass to he formed be of sufficient tractability to be easily introduced into the cavities of the mould by kneading, and that, when pressed, It be of sufficient tenacity as not to bend or yield upon removal. It must, therefore, acquire consistency, and dry in the mould—a condition which Tenders it absolutely necessary that the moulds he constructed of substances of a porous nature, otherwise the pieces would adhere and lose their shape upon removal. The moulds are, therefore, generally formed of gypsum—plaster of Paris—and sometimes of burned clay, and are of every variety of size and pattern, a complete set of pattarns being required for evory new design, and for every size of the same pattern. Moulds for plates, dishes, and other shallow articles, consist of only one pioco, while for jugs, vases, and more elaborate forms, several pieces or moulds are employed. 

The mode of making the moulds for plates and dishes, and the subsequent operation of moulding, aro as follows —Upon a model, a—Fig. 476—composed of either metal or gypsum, and turned in relief to... 

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