468 OZONE 



Marechal and Tessie du Mothay prepare oxygen by heating the manganates, per- 

 manganates, chromates, and ferrates of the alkalis, in a current of steam. The 

 manganate of soda is used for this purpose in America. 



The manganate is crushed to a coarse powder, and is then placed in elliptical 

 retorts, 7 feet long, 1 foot wide, and 2 feet deep. These are placed horizontally, the 

 ellipse being vertical. A current of super-heated steam is then passed through the 

 mass, at first slowly, afterwards more rapidly ; when the heat has become sufficiently 

 high, part of the oxygen is eliminated, and passes off with the steam, which latter, 

 being condensed, oxygen remains in a state of tolerable purity. The condensers used 

 are similar to those employed in gas-works to separate the less volatile constituents 

 from the coal-gas. They are simply a system of upright cast-iron U-pipes inverted. 

 The water thus formed is sufficient in quantity to wash all soluble impurities from the 

 gas. Farther impurities are removed in a scrubber, whence the oxygen passes, fit for 

 use, into the gas-holder. 



After the manganate of soda has been subject to the action of the steam for about 

 ten minutes, the current is shut off, and atmospheric air blown in its place, the 

 effect of which is to re-oxidise so much of the soda-salt as has parted with its oxygen. 

 The nitrogen of the air escapes. After ten minutes the air is cut off and steam re- 

 introduced, which, as before, carries with it oxygen into the condensers. 



Some difficulties have been found in working this process. Theoretically, the man- 

 ganate should continue to yield oxygen ad infinitum ; but, in practice, it is found that 

 after being some time in use it loses its porosity, and consequently does not permit the 

 steam to act through its whole mass. It becomes, therefore, necessary to recharge 

 the retorts after not very long intervals. It is believed that, if the steam could be 

 kept perfectly dry throughout the process, a result much more nearly approaching that 

 predicted by theory, would be attained to. 



OZOKERITE or OZOCERITE. A mineral wax found in the Urpeth Colliery, 

 Newcastle-on-Tyne, at Uphall in Linlithgowshire, and in one or two of the collieries, 

 in South Wales. Its composition is, usually, hydrogen 13'79, carbon 86'20. Ozokerite 

 is found in considerable quantity in Moldavia and in Galicia, and has been used 

 for the distillation of paraffin and the manufacture of candles. See CANDLES; 

 PARAFFIN. 



OZONE and ANTOZOZiTE. The most convenient method' of procuring ozone, 

 or rather an ozonised atmosphere, is to place in a large bottle of air, which can be 

 completely closed, a stick of phosphorus freshly scraped. Sufficient distilled water 

 should be poured into the bottle to partially cover the phosphorus ; the vessel should 

 then be closed with the stopper, and kept in a room at a temperature between 60 and 

 70. The phosphorus is oxidised in the bottle in the iisual way ; and, during this 

 process of oxidation, a portion of the oxygen passes to the state of ozone, and is 

 diffused through the air in the bottle. The test for its presence is a slip of paper 

 moistened with a solution of starch and iodide of potassium. When ozone is pro- 

 duced, this paper on immersion acquires a blue colour, owing to the oxidation of the 

 potassium, and the production of iodide of starch. If a similar slip of paper is put 

 into a similar bottle of air containing distilled water without phosphorus, no change 

 is produced. In a warm room, the evidence of the presence of ozone in a bottle is 

 usually procured in about ten or twelve minutes ; but the maximum quantity of ozone 

 is found in it from two to ten hours. Only a small part of the oxygen (from l-50th 

 to 1 -200th) appears to undergo this change; and if kept long, the ozone may be lost 

 by combining with the oxidising phosphorus. So if the iodide paper be left in 

 the bottle, the blue colour will after a time disappear by the ozone combining with 

 the iodine to form iodic acid. It is not produced in dry oxygen, nor in humid air, 

 or in oxygen mixed with certain gases or vapours which prevent the oxidation of 

 the phosphorus ; but it appears to be more readily produced, ceeteris paribus, when 

 oxygen is mixed with nitrogen, hydrogen, or carbonic acid. By washing and 

 decautation, the ozonised air, which is quite insoluble in water, may be deprived of 

 the phosphorus-vapour associated with it, and kept in well-closed bottles. It is 

 speedily lost by diffusion. Graham found that ozone traversed dry and porous stone- 

 ware. Ozono may be produced on a small scale by placing a piece of phosphorus 

 with water in a watch-glass, and inverting over this another glass containing the 

 test-paper or liquid. 



Ozone is produced by passing the electric spark silently into pure and dry oxygen. 

 Fremy and Becquerel found that pure oxygen contained in a sealed tube, when treated 

 for a sufficient time with a series of electric sparks, underwent a complete conversion 

 into ozone, as the whole contents of the tube, when broken, were absorbed by a solu- 

 tion of alkaline iodide, in which it was immersed. In the electrolytic decomposition 

 of water, the oxygen at the positive pole has ozonic properties, provided the poles 

 employed are of gold or platinum. The hydrogen evolved gave no indication of 



