228 ANNUAL OF SCIENTIFIC DISCOVERY. 



scientific research, which is strikingly illustrated by the substance and 

 form of these results, and of which instances are probably to be found 

 in the history of many others. The explanation of the above reactions 

 consists in a combination of two modes of reasoning, which were de- 

 veloped by different schools, and for many years were used indepen- 

 dently of one another. Gerhardt, to whose researches and writings, 

 some important steps in the doctrine of types are owing, formerly be- 

 lieved the truths which he saw from that point of view, to be incom- 

 patible with the idea of radicals, but he now joins those chemists 

 who find in each of these notions a necessary and most natural com- 

 plement to the other. May we not hope that such may be the result 

 mother cases of difference of opinion on scientific questions, which the 

 progress of knowledge will show to have been owing to the incom- 

 pleteness and one-sidedness of each view, rather than to anything ab- 

 solutely erroneous in either ? 



ON THE INFLUENCE OF THE ELECTRIC SPARK IN CONVERTING 

 PURE DRY OXYGEN INTO OZONE. 



At a recent meeting of the Royal Society, Prof. Faraday gave a 

 communication respecting the late researches of Fremy and Becquerel 

 on the conversion of oxygen into ozone. The electric discharge from 

 different sources produces this effect, but the high intensity spark of 

 the electric machine is that best fitted for the purpose. When the 

 spark contains the same electricity, its effect is proportionate to its 

 length ; for at two places of discharge in the same circuit, but with 

 intervals of 1 and 2, the effect in producing ozone is as 1 and 2 also. 

 A spark can act by induction ; for, when it passes on the outside a 

 glass tube containing within dry oxygen, and hermetically sealed, the 

 oxygen is partly converted into ozone. Using tubes of oxygen which 

 either stood over a solution of iodide of potassium or, being hermeti- 

 cally sealed, contained the metal silver, the oxygen converted into 

 ozone was absorbed ; and the conversion of the whole of a given quan- 

 tity of oxygen into ozone could be thus established. The effect for 

 each spark is but small ; 500,000 discharges were required to convert 

 the oxygen in a tube about 7 inches long and 0.2 in diameter into 

 ozone. For the details of this research, see the "Annales de Chimie" 

 1852, xxxv. 62. Mr. Faraday then referred briefly to the recent 

 views of Schonbein respecting the probable existence of part of the 

 oxygen in oxy-compounds in the ozone state. Thus of the peroxide of 

 iron, the third oxygen is considered by him as existing in the state of 

 ozone ; and of the oxygen in pernitrous acid, half, or the two latter 

 proportions added when the red gas if formed from oxygen and nitrous 

 gas, are supposed to be in the same state. Hence the peculiar chemi- 

 cal action of these bodies ; which seems not to be accounted for by the 

 idea of a bare adhesion of the last oxygen, inasmuch as a red heat can- 

 not separate the third oxygen from the peroxide of iron ; and hence 

 also, according to M. Schonbein, certain effects of change of color by 

 heat, and certain other actions connected with magnetism, c. 



