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Last week, we visited a large factory where they make window glass. ______ Special rollers too 1 Last week, we visited a large factory where they make window glass. ______ Special rollers took hold of the sheet at either side and carried it upwards. ______ Here some men lowered a metal frame into the liquid. ______ They then fed the mixture into a big hot oven. ______ Our guide told us that at this stage it was necessary for the glass to cool slowly as this would make it very strong. ______ At a height of 30 feet, the sheet of the glass became cool and another machine cut it into big pieces which workmen stored away together. ______ Then they added some broken glass to the mixture as this helps it to melt. ______ We first saw workmen mixing sands and other materials together in the right amounts. ______ At the far end of the oven, a stream of liquid glass came out. ______ As the frame came up, it pulled away a hot sheet of glass. 11 Finally the glass was ready for use.