Pyrex hardness

Place 50 g. of o-chloronitrobenzene and 75 g. of clean dry sand in a 250 ml. flask equipped with a mechanical stirrer. Heat the mixture in an oil or fusible metal bath to 215-225° and add, during 40 minutes, 50 g. of copper bronze or, better, of activated copper bronze (Section 11,50, 4) (1), Maintain the temperature at 215-225° for a further 90 minutes and stir continuously. Pour the hot mixture into a Pyrex beaker containing 125 g. of sand and stir until small lumps are formed if the reaction mixture is allowed to cool in the flask, it will set to a hard mass, which can only be removed by breaking the flask. Break up the small lumps by powdering in a mortar, and boil them for 10 minutes with two 400 ml. 

Steel, nickel, Monel and Pyrex for dry gas. For moist gas hard rubber and paraffin wax... 

Phosphorus pentafluoride Phosphorus trifluoride F T Steel, nickel, Monel and Pyrex for dry gas. For moist gas hard rubber and paraffin wax Steel, nickel, Monel and the more noble metals and Pyrex for dry gas... 

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