Muffle glass

Consult your instructor on how to use a muffle furnace safely and remember safety glasses. 

Procedure. Weigh 2 g of the oven dried sample ground to 1 mm into a porcelain or glass crucible and place in a cool muffle furnace. Increase the temperature to 550°C and ash for 2 h. Cool and dissolve in nitric acid solution, make up to 20 ml and store in a polythene capped tube. Allow to settle before transferring to another clean sample tube by decanting or using a polythene Pasteur pipette. Analyse the solution by AAS or ICP according to the manufacturer s recommendations. 

Determining the Equivalent of Lead. Roast a clean porcelain bowl in a muffle furnace at 4C0-450 °C, and after cooling it in a desiccator, weigh it with an accuracy up to 0.01 g. Put about 0.5 g of granulated lead in the bowl and weigh it with the same accuracy. Pour 10 ml of a 40% nitric acid solution onto the metal, cover the bowl with a watch glass, and place it in a water bath. See what happens. Write the equation of the reaction. 

The glass content was determined by resin bum-off of ring segments in crucibles in a muffle furnace. The void content was determined by a method of optical microscopy previously reported (6). Horizontal shear was measured by the Short Beam method (1). 

A general procedure is to place the weighed sample into a platinum or silica glass crucible and heat it in a muffle furnace to a white ash. The temperature should be kept at 400 to 450°C if any of the more volatile metals are being determined. Salts or sulfuric acid may be added, if needed, and a final ashing step can be done with hydrofluoric acid if required. The residue is then dissolved in concentrated nitric acid and warm water, and diluted to volume. The final concentration of acid should be between 1 and 5%. 

The beam bending viscometer is depicted in Figure 10.10. A glass beam of uniform cross section is extended across an alumina muffle. Using a sapphire or fused silica hook, a load is applied at the center of the beam. The deformation rate of the center of the beam is measured, and the viscosity is determined... 

The cast iron muffle was replaced by a fireclay brick muffle. The arch was made of carborundum which conducted heat well and withstood the effect of sulphuric acid. The outer brickwork was circular in shape and not rectangular as in the Mannheim furnace. Consequently, the surface area of the muffle was smaller so that the loss of heat due to radiation was reduced to a minimum. The interchangeable blades on the four arms of the stirring device, which revolved at a velocity of 1 to 2 r. p. m., were made of carborundum which resists to wear and does not pollute the product either with iron or chromium. This is of great importance when manufacturing sulphate for glass works. 

Our overall approach to matrix elimination and Am and Pu preconcentration is shown in Figure 2. One hundred grams of a dried Northern Illinois soil sample is muffled at 500"C for 3 hours in a glass beaker. Four hundred pg of Sm(III) and the appropriate amounts of Pu(III)/(IV) and Am(III) tracers are added to the muffled soil sample. The sample is then leached with 300 mL of 6 M HCl at 90 C for 2 hours with stirring. After cooling, the supernatant is separated by centrifugation for 15 minutes at 5000 rpm. The residue is washed two successive times with 75 mL of 6 M HCl and the combined supernatant plus rinses (-450 mL) is filtered to eliminate any suspended particles. 

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