80 Transactions of the 



(4) Siemens has devised an ingenious api^aratus for the 

 production of ozone by induction. His apparatus consists 

 ' of a glass tube, about the size of an ordinary test tube 

 coated with tin foil, or still better, silvered and enclosed 

 in an outer tube lined outside with tin foil. The two tubes 

 are sealed together at the neck of the outer one, and so 

 adjusted that the space between them shall be as nan'ow 

 as possible. At the projecting end of the inner tube is a 

 brass button, which is connected by a spring with one of 

 the binding screws on the frame of the apparatus, which 

 screw is to be connected with one of the terminals of the 

 secondary coil of an inductorium, and the other, with another 

 binding screw in metallic communication with the coating 

 of the exterior tube. The apparatiis is, in fact, a sort of slit 

 Leyden jar ; and air or oxygen admitted through the lateral 

 tube becomes, during its passage through the apparatus, 

 powerfully ozonised.' 



(5) By the electrical decomposition of water, acidulated 

 slightly by means of an acid, as sulphm'ic (H2SO4), by means 

 of the galvanic battery ; by this process at the negative pole 

 oxygen and ozone are developed in a mechanical mixture 

 from which they cannot be separated by any means at 

 present known. Hydric dioxide (HgOj) is also formed in 

 minute quantities. 



(6) By plunging a hot glass or iron rod into a bottle 

 contauiing air or oxygen mixed with the vapour of ether 

 (C4H10O), alcohol (CjHgO), oil of turpentine (CioHjg), sul- 

 phuric-dioxide (SO2), and some other ethereal oils and 

 hydro-carbons. The residual contains peroxide of hydrogen 

 (H2O2), atid if agitated with a few drops of a solution of 

 potassic chromate (K2CrOj slightly acidulated with sul- 

 phuric acid (H2SO4), a blue solution of perchromic acid 

 (HCr04) is formed. If this experiment (when performed 

 with ether) is varied by the substitution of oxygen for air 

 and a heated glass tube for the rod, an explosion takes place. 

 This is explained by the supposition that ozone is liberated 

 in such large quantities that the ether is oxidised with so 

 much violence as to cause an explosion. 



(7) By heating together three parts of sulphuric acid 

 (H2SO4) and two parts of permanganate of potassium 

 (KMn04) ; this Boettger states will continue to give off ozone 

 for months. 



(8) Houzeau states that the oxygen evolved fi-om baric- 

 dioxide (Ba02) on the addition of sulphuric acid (H2SO4), 

 contains ozone, and that the gas so prepared possesses its 



