Sulfur continued melting point

The copper remaining in lead after the above operation is removed by matte formation. Finely divided sulfur is added to molten lead at temperatures slightly above its melting point, and the melt is stirred continuously. Copper sulfide forms and floats on the surface, leaving the bullion substantially free of copper (less than 0.005%). The standard free energies of formation of cuprous sulfide and lead sulfide are about the same the observed separation must, therefore, be due to kinetic factors or to the influence of certain minor impurities that are present in the lead. 

An element is a substance that cannot be broken down into simpler substances by ordinary chemical means. A chemical compound is a substance made up of two or more elements that have been chemically bonded together. Scientists believe that solid sulfur compounds do not exist on Venus like they do on Earth because, at about 900° Fahrenheit (480° Celsius), the surface temperature on Venus is too hot for them to form in the first place. This temperature is well above the melting point of sulfur (235°F [ 113°C]). Therefore, instead of being incorporated into rocks, the sulfur on Venus continues to float around in the atmosphere in the form of the chemical compound sulfur dioxide (S02). 

Methyl methacrylate (melting point -48°C, boiling point 100°C, density 0.9394, flash point 9°C) is produced by the acetone cyanohydrin process in which the acetone cyanohydrin (from the reaction of acetone with hydrogen cyanide, q.v.) is reacted with sulfuric acid to yield methacrylamide sulfate, which is further hydrolyzed and esterified. The process is continuous. 

Six gms. of nitro compound are dissolved in 50 mL. of 95% ethanol, and 20 gms. of zinc pellets (20 mesh) are added, together with a few drops of ferric chloride. Then while stirring and with the temperature maintained at 40° C., 35 mL. of 12 N. sulfuric acid are added, drop wise, during the course of 1 hour. Stirring is continued at 40° C. for six hours, then for an additional 18 hours at 20-25° C. The solution is then decanted from the zinc, made very alkaline, and extracted with ether. Concentration of the latter yielded crystals of 2-amino-2-methyl-l-phenyl-1-propanol having a melting point prior to purification of 80-89° C. Recrystallization from hot benzene raised the melting point to 99-99.5° C. 

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