Fig. 37. Making Sheet Glass.
"For this trial, measure out eight quarts of sand and two quarts of the lime, and after depositing it in the crucible, we are ready for the heat."
In a short time, with the assistance of the blower, which has already been described, the sand began to melt. It was now stirred so that the elements were thoroughly mingled. During the melting period the dross or impurities which came to the top were skimmed off, and when no more of the impurities collected the Professor stated that they might remove the crucible and pour the melted mass into small pockets, which they had previously formed with clay.
"Why not pour this on the slate forms we made?"
"Because we must know that we have a good sample of glass, and for the further reason that the product we are now to make should have some glass in it that has already been fluxed before, and we now have such a manufactured material."
The material which had been cast in the pockets was broken up with a hammer, as soon as it had cooled, and its appearance noted.
"I see we shall have to use less lime."