Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: 25. Reduction of cupric oxide by hydrogen. — A small quantity of powdered cupric oxide is placed on a porcelain crucible lid, the ring of which is pressed into a slit in a cork fastened on the end of a long iron wire. This arrangement permits of thrusting the crucible lid up into an atmosphere of hydrogen in a dry liter cylinder. The cylinder is first filled with hydrogen and clamped in a vertical position with the mouth downwards, the mouth being kept closed by holding a glass plate against it. The cupric oxide is heated from above with a small Bunsen flame till quite hot and then thrust rapidly up into the hydrogen. Soon moisture condenses on the side of the jar, and on allowing the cupric oxide to cool in the atmosphere of hydrogen for a few minutes and then withdrawing it, it will be seen to have the 'characteristic red color of metallic copper. Crucible lid ; cork ; stout iron wire; liter cylinder of H; CuO powder. OXYHYDROGEN GAS AND WATER 26. Formation of water by the combustion of hydrogen in air. — (a) By passing the products of combustion of hydrogen in air through a U-tube, a considerable quantity of water is condensed in a short time. In the apparatus (Fig. 31) one limb of the U-tube is fitted with a rubber stopper and a glass elbow connected with the suction-pump. The other limb is fitted with a cork containing the small end of a bent thistle-tube. Hydrogen, dried by passing through a U-tube containing calcium chloride, is allowed to burn from a blowpipe jet held immediately under the bulb of the thistle-tube. The rate of suction must not be such as to cause the firstlimb of the U-tube to become warm enough to vaporize any water that may have condensed. Apparatus (Fig. :51); U-tube ; bent thistle-tube ; metallic blowpipe jet; CaCl2 drying tube. (6...