Heating methods sand baths

Wetness impregnation method. Water solution of Ni nitrate (120 mg/ml) was added to powder of ATLS. Solvent excess was evaporated by heating on sand bath and then under lamp. The sample impregnated was calcined at 700°C for nitrate decomposition. 

Landers et al. [97] and others [98] have described a wet digestion method for the determination of total sulphur in soils. In this method the sample (1.50-500mg) is placed in a digestion flask and heated in a sand bath to dryness at 250°C with 3ml of sodium hypobromite solution. The residue is resuspended with water, neutralized with formic acid, and then hydriodic acid reduction of the sample is followed to quantitatively recover the inorganic sulphate formed by wet oxidation. 

Many chemical treatises give instructions on the use of different kinds of furnaces. Besides the calcinatory furnaces for reducing metals and minerals to a fine powder, there was the athanor. This contained a deep pan of sifted ashes. The material to be heated was placed in a firmly sealed container and covered with the ashes. This method is rather like a modem chemist s sand bath. Then there was the descensory furnace, which had a funnel with a lid. Liquid could flow down the stem of the funnel into a receptacle. Another sort of furnace was known as the dissolving furnace. It consisted of a small furnace supporting a pan full of water. In the pan were rings to hold glass containers. It... 

Catalysts Commercial and laboratory prepared catalysts were used. Catalysts were prepared by the coimpregnation method as it has been reported before (7). The support was a cubic gamma alumina. It was first impregnated with distilled water (three times its pore volume), placed in a flask and then an aqueous solution of H PtCl and NH ReO was added. The mixture was stirred and then heated gently at 70°C in a sand bath. The solution was evaporated slowly and under stirring, until a dry powder was obtained. The catalysts were then heated in a stove at 120°C overnight. They were then calcined in air at 500°C for 4 h, and finally activated by reduction in hydrogen at 500°C for 4 h. Catalysts properties are summarized in Table 1. 

Pure Se is slowly added to pure, concentrated, heated nitric acid, the solution is evaporated to dryness on a sand bath, and the residue is heated until sublimation begins. It is then absorbed in water and, to remove all Se04 present, Ba(OH)s solution is added dropwlse until the precipitate ceases to form. The solution is filtered and reevaporated to dryness while stirring. The crude product is powdered and repeatedly sublimed. For very pure material the compound is sublimed in pure as in method I. For many purposes, however, it is sufficient to sublime it two or three times from a porcelain dish into an inverted beaker or an Inverted funnel... 

With this method, a measured or weighed water sample is heated in a suitable evaporation vessel until the water is almost completely evaporated and only those substances which were previously dissolved in the water and are not volatile at the selected temperature remain in the dish. The vessel can be a weighed platinum, glass or porcelain dish, and the sample is heated over a boiling water bath, a heated sand bath, an electric hot plate or an air bath. The evaporation residue can then be dried to constant... 

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