Cooling clay-filled

Thirty-six grams of powdered stibnite (SbaS8) are ground thoroughly in a mortar with 43g of anhydrous sodium sulfate and 16g of charcoal. The mixture is placed in a large clay crucible (the latter should be about half-filled), covered with a thin layer (about % inch) of charcoal and heated over a Meker burner to a state of quiet fusion, then ten minutes longer. The melt is poured into an iron dish, allowed to cool and then powdered. The material is then boiled under reflux with 7g of sulfur powder in 300ml of water, suction-filtered, and the product is isolated as described in (I). 

NaBr 2H20, and 3% NaBrOg. The remainder is water. The crystal mass is separated on a glass frit and immediately recrystallized from 2% NaOH in order to obtain the maximum possible separation of NaBr and NaBrOg. About 30 ml. of base (at 20°C) is used for each 100 g. of crude material. The solution is then filtered and the filtrate cooled with an ice-salt mixture. The crystals that are filtered off (when damp, about 18 g. from 100 g. of crude crystals) are dried for 1-2 hours on a precooled (0°C) porous clay plate placed in a desiccator (0°C) filled with silica gel. 

A low vertical cylinder closed off with a rubber stopper serves as the electrolysis vessel and contains the sulfate solution. The anode is a piece of Pt sheet immersed in a clay cell filled with 20% H3SO4. The cell is partially immersed in the Ti (TV) sulfate solution and is surrounded by four amalgamated lead strips, also immersed in the solution. The stopper on the outer electrolysis vessel has holes for the clay cell and for the inlet and outlet gas tubes. The electrolysis is carried out in a constant stream of COg and with efficient water cooling. The current density is 0.06 amp./cm. at 24 v. for the first six hours, then 0.33 amp./cm. at the same voltage for an additional six hours. This reduces all the Ti (IV) sulfate to Ti (III) sulfate the latter precipitates as an H3804-containing hydrate (fine, pale light violet crystals). 

Very pure CuO (15 g.) is dissolved in a clear, carbonate-free solution of 500 g. of NaOH in 330 ml. of HsO (brief refluxing). The dark-blue solution is cooled to 110 C and carefully diluted by adding 140 ml. of H3O through the reflux condenser (use a funnel). The small quantity of unreacted CuO is then filtered off, collecting the filtrate in a preheated Erlenmeyer flask of refined silver. The Erlenmeyer flask is protected by a Peligot tube (filled with 50% KOH) and kept in an electric drying oven for six days at TO C to allow the filtrate to crystallize. The mixture is then filtered the crystals are washed with some 50% and 45% sodium hydroxide (once each) at room temperature and dried on a clay plate over H3SO4. Yield 13 g. 

Clays in general shrink when fired because the pore spaces gradually become filled with molten material which eventually, on cooling, solidifies to form a glass. If the firing is sufficiently prolonged, all the pore spaces become filled and the body is then said to be vitreous, and has no porosity. 

Cebe and Rimt [56] used DSC to investigate the effect of inclusion size, shape and filler surface treatment with stearic acid on the crystallinity and gas permeability of HDPE composites filled with micron sized calcite or nanosized calcium carbonate or clay. It was foimd that spherical inclusions had no effect on gas permeability whereas the plate-like inclusions reduced gas permeability and that neither the calcium carbonate nor the clay nucleated the crystallisation of HDPE imder slow cooling conditions. 

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