harpness and color. Itis not a sand in the ordinary sense of the word,but is a quarried rock which has been crushed.This accounts for the uniformity of its color,which is so necessary in producing a steely-bluewhite glass, which is to be used for giving theprismatic colors caused by the cutting…
Portland · Glass · Cement · Scientific American · Device · Cut glass · Sir william · Portland cement · American supplement · Sewing machine · Speed trials · American supplements · Jerome park · Shunt coil
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