A Treatise on Casehardening and the Heat-Treatment of Steel by Sodium CyanideA Treatise on Casehardening and the Heat Treatment of Steel by Sodium Cyanide The Cassel Cyanide Co., c1950s, lightly illustrated with black and white photographs and technical line drawings, fold out diagrams, paperback Very Good Condition, a little edge and shelf wear, a little rubbing and bumping to edges and corners, previous owners details stamped on front cover, rear cover and title page, signature on front cover (see photographs)