QUANTITATIVE ANALYSIS 507 water in the top of H provides an indication of the time required: when the water begins to boil, the heating should be at once stopped. Then lower the bomb into cold water, and when it is thoroughly cold, unscrew and remove the outer case GH, rinse the outside of the bomb A with distilled water, dry it with a cloth. Prise off the lid C: if the ignition has occurred, fused lumps of peroxide will be seen, and the appearance of the mixture will have clearly changed. (If no ignition has occurred, replace the lid C and heat the encased bomb for a longer time: avoid overheating, which may melt the lead washer.) Using distilled water from a wash-bottle, thoroughly rinse the inside of the lid C into a 150 ml. beaker. Carefully wash the outside of the bomb A similarly and discard the washings. Then place A on its side in the beaker, and add water until it is half-immersed. Cover the beaker with a watch-glass, and heat it gently until the peroxide has decomposed, and evolution of oxygen has ceased. Using stainless steel forceps or
This is the end of the preview. Sign up
access the rest of the document.