Artificial Gravel

1919 Scientific American  
341 ware in the past few decades. When the war broke out, the stoneware works of this country were not able to deal with the demands, and tantiron vessels, which can be made in a few days, while good stoneware re quires months, were largely adopted. Valentiner plants comprising, a still, condenser and coils, built up of pipes and return bends flanged together, all of tantiron, are now made. The denitrating tower is an interesting novelty. The spent acid of nitroglycerin works consists of
more » ... sulphuric acid, which has to be concentrated again, and some nitric acid, which is to be regained by distillation. There may also be small globules of oily nitroglycerin which might coalesce if the evaporation were carried on in pans. The tower, 15 ft. high, is built up of socket pipes, 14 in. diameter, and is packed with quartz fragments; the acid enters at the top
doi:10.1038/scientificamerican05311919-341csupp fatcat:gfqdv6u4hfbijoakvdjo6rgfxa