By heating it in an enclosed high-temperature steam boiler the siliceous particles were bound together and could be moulded or worked into filtering slabs, vases, tombstones, decorative architectural work, emery wheels and grindstones.
By heating it in a sealed high-temperature steam chamber, the siliceous particles were united and could be shaped or formed into filtering slabs, vases, tombstones, decorative architectural elements, abrasives, and grinding stones.