Crucible block

Experiment ii. — Supplies Powdered iron, zinc dust, crucible and support, glass rod used in Exp. 10, crucible block. 

In carrying a crucible to and from the scales, it should not be carried in the hand nor by the forceps, but placed in the crucible block which is shown in Fig. 22. Support the crucible as before and heat it for about ten minutes. Heat with a low flame at first and gradually increase the heat. Finally stand the burner under the crucible, taking... 

Supplies Porcelain crucible and cover, powdered magnesium, forceps, pronged tripod or similar support, crucible block. 

Supplies Crucible and cover, forceps, support (as in Exp. 15), dry, powdered potassium chlorate, crucible block. 

Supplies Porcelain crucible and support, crystallized barium chloride, forceps, crucible block. 

The problem of the cooling of hot vessels within a desiccator is also important. A crucible which has been strongly ignited and immediately transferred to a desiccator may not have attained room temperature even after one hour. The situation can be improved by allowing the crucible to cool for a few minutes before transferring to the desiccator, and then a cooling time of 20-25 minutes is usually adequate. The inclusion in the desiccator of a metal block (e.g. aluminium), upon which the crucible may be stood, is also helpful in ensuring the attainment of temperature equilibrium. 

Other types of refractory that find use are forsterite, zirconia, and zircon. Acid-resisting bricks consisting of a dense body like stoneware are used for lining tanks and conduits in the chemical industry. Carbon blocks are used as linings for the crucibles of blast furnaces, very extensively in a number of countries and to a limited extent in the United States. Fusion-cast bricks of mullite or alumina are largely used to line glass tanks. 

Torsi et al. [395] have carried out a systematic investigation to establish the potential value of such an apparatus. The apparatus is basically an electrothermal device in which the furnace (or the rod) is replaced by a small crucible made of glassy carbon. Figure 5.10 provides an overall view of the apparatus. Figure 5.11 shows a block diagram of the electrolysis circuit the crucible (6) acts a cathode, while the anode is a platinum foil dipped into either the sample solution reservoir (1) or the washing solution reservoir (2). Pre-elecrolysis was performed at constant current with a 500 V dc variable power supply (5). Under these conditions, the cathode potential is not controlled, so that other metals can be codeposited with lead. 

Chenot An early steelmaking process. Iron ore was first reduced to sponge iron this was mixed with charcoal, manganese, and resin and compressed into small blocks. These blocks were then melted as in the Crucible process. Invented by A. Chenot in France in 1846 and operated on a small scale in Sheffield in the 1860s, but abandoned after the introduction of the Open Hearth process. 

Some of HTCVD s initial challenges have been solved. For example, using a coaxial injector solved the blocking of the inlet. Another issue is the purity of the graphite material, which may be overcome using properly coated graphite crucibles. 

The isopiestic method described elsewhere (8, 9,10) was used to obtain the experimental data of water activity of the aqueous solutions. In our arrangement, eight gold-plated silver crucibles were embedded into hollows of a copper block and placed in the glass vacuum desiccator. The crucibles were provided with covers which can be handled from inside. Three desiccators were placed in a water bath (maintained at 25 0.01 °C) on a brass construction which moved from one side to the other. This movement, aided by a moving glass bead in each crucible, mixed the solutions. The desiccators with the samples were evacuated to the pressure of about 20 torr and the evacuation after a time interval was repeated 2-3 times. The time needed for the establishment of equilibrium was... 

Carbon brick and block are used to line the cupola well (73) or crucible. When propedy installed and cooled carbon linings last for many months or even years of intermittent operation. Their resistance to molten iron and both acid and basic slags provides not only insurance against breakouts but also operational flexibility to produce different iron grades without the necessity of changing refractories. Carbon is also widely used for the tap hole blocks,... 

Manufacturing of industrial of industrial carbons, graphite electrodes, anodes, midget electrodes, graphite blocks, graphite crucibles, gas carbons, activated carbon, synthetic diamonds, carbon black, channel black, and lamp black... 

Experiment 82. — (a) Cover the bottom of a Hessian crucible with a thin layer of sand. Put on the sand a small piece of wood, a small, compact wad of cotton, a small bone, and a lump of starch. Fill the crucible loosely with dry sand, and slip it into the ring of an iron stand. Heat with a flame which extends just above the bottom of the crucible until the smoking ceases (approximately a half hour)-. After the crucible has cooled sufficiently to handle, pour the contents out upon a block of wood or an iron pan. Examine the contents. What is the residue What is hereby shown about the distribution of carbon ... 

The carbonization experiments were conducted on anhydrous beech cubes of 2 cm side in a laboratory electrical kiln. The wood blocks were placed in crucibles closed by a cap. Samples were introduced into the kiln at room temperature. 

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