Show A now material has been found to bo mixed with cement for hnrdonlng tho surfaco ot concroto floors. The mixture contains !)5 per cent of iron dust which Is addod to dry cement In tho proportion of 15 pounds to overy 100 pounds. Ono part ot this dry mlxturo Is then mixed with two parts of sand. When this Is mixed with water and hppllcd to tho floor ns a top coat to 11 thickness ot ono halt to onu Inch It makes n splendid surfaco sur-faco which Is not slippery mid at the snmo tlnio is wntorproof. |