and its relation to Ozone. 61 



primary current. This interruption was, as usual, effected by 

 the current itself, through the agency of a small hammer 

 and an electro-magnet. The number of the sparks produced 

 may be readily calculated from the tone caused by the vibrations 

 of the small hammer. This tone, which naturally varies in 

 height and depth according to circumstances, was on the average 

 E in the great octave. The number of vibrations corresponding 

 with this sound give eighty-two strokes in a second; this repre- 

 sents more than two million sparks in the course of the experi- 

 ment, which lasted four hours*. The apparatus in which this 

 stream of sparks was employed is represented in fig. 5. 



The porous cell a, which is more exactly represented at fig. 6, 

 contains the positive pole, and stands in a glass vessel filled with 

 diluted sulphuric acid and some sulphate of iron, and kept cool 

 from without. This receives the negative pole outside the cell, 

 in such a manner that the hydrogen evolved is completely sepa- 

 rated from the oxygen. The oxygen gas passes through the 

 small globe apparatus b (fig. 5), filled with sulphuric acid, into 

 the tube c, which is surrounded in the middle with fine plati- 

 num foil, and kept at a strong red heat by means of a Berzelius' 

 lamp during the whole course of the experiment. By this means 

 the ozone formed, as well as any hydrogen which might possibly 

 have been carried away by diffusion, is converted into water. 

 From this portion of the apparatus the stream passes into the 

 globe cl (fig. 7), filled with fragments of iodide of potassium, 

 which is separated from the tube e, filled with powdered chemi- 

 cally-pure phosphoric acid, by a stopper of asbestos which has 

 been heated to redness. The gas, which has been completely 

 freed from ozone and watery vapour in these two pieces of appa- 

 ratus, passes lastly into the small tube f, which is about half a 

 line in diameter, and into which the platinum wires connected 

 with the induction apparatus for the production of the sparks 

 are fused. This part of the apparatus is united with the ante- 

 rior portion, blown out of a piece of tube, in the manner pre- 

 viously described, and the whole tube containing the platinum 

 wires coated with a film of anhydrous phosphoric acid. The 

 small globe apparatus h, filled with solution of iodide of potas- 

 sium, is ground air-tight into the dilated mouth g of this tube. 



The following was the system followed during the experi- 

 ments : — First of all, a stream of oxygen was driven at a measured 

 speed through the apparatus for three hours by means of the 

 polar plate ; during this time the piece of tube c was kept at a 

 red heat, and the induction spiral inactive. Neither the iodide 

 of potassium in the globe d, nor the film of phosphoric acid in 



* For every stroke corresponds to one closure and one rupture of the 

 circuit ; hence to two sparks.— Ed, 



